KRISHNA BEACH RESORT, PALLIYAMMOOLA.

A Technical Report on

Daikin VRV- IV A/c system & Renewable Energy SystemNovember 2015 – October 2016

Divya.K.VB.Tech EEE

Electrical Engineering TraineeKrishna Beach Resort,

Palliyammoola,P.O. Alavil,

Kannur- 670 008

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Contents

1. Krishna Beach Resort : 032. Air conditioning system : 043. Sewage Treatment Plant : 104. Water Treatment Plant : 135. Waste Management : 15

Bio gas plant : 15Incinerator : 17

6. Fire fighting measures : 217. Security : 26

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Krishna Beach Resort

Krishna beach resort, a holistic resort for body, mind and soul is one of the

prestigious project of Krishna Jewels, Kannur is situated in Palliyamoola, near

Payyambalam. Which is hardly 5Km from Kannur Town. Main attraction of the resort is its

architectural beauty with laterite stones. Our lobby is designed with a unique architecture

symbolizing different chakras in a human body. It consists of a dome that provides natural

daylight.

There is a separate waiting lounge for the guests with sculptures of prophets and

philosophers. There are 3 restaurants located on different floors. The coffee shop is located

at the ground floor level. It provides buffet choice with a total number of 50 covers. It

provides a variety of dining options from sandwiches to Kerala Delicacies. The fine dining

Specialty restaurant is located at first floor with a total of 50 covers and serves delectable

continental cuisine. To promote our Local cuisines, we have Kerala buffets located in the 3rd

floor with a total 50 cover. There is an exclusive art gallery showroom that showcase local

arts, handicrafts, antique items etc.

The resort is equipped with a banquet hall located at first floor that can host a

reception up to 600 guests. There are 2 family get together rooms that cater to the needs of

an informal gathering up to 50 guests. The premise also includes an open air roof top

banquet, which has a room for 500 guests. The open air space gives a breathtaking

backdrop of the Krishna Beach horizon.

A business center is located behind the reception where the guest can avail the

facilities like printing, faxing, internet, Xerox, etc. The space for Health club, spa and fitness

center has been allotted in a separate building outside the main block. There is a separate

space allotted to the parking area for the guest with a specific driveway of 4m wide where a

total number of 100 cars can be parked. One of the remarkable feature of the hotel is the

Open theatre with the splendid view of Shiva’s statue which has a seating capacity of 1000 .

A separate room has been designated only for the differently abled guest located at

ground floor and situated just aside reception and is designed with features for easy

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accessibility of a differently abled guest The facilities include a door that allow wheelchair

access, low height furnitures, low peep hole, cupboard having sliding doors with low clothe

hangers, audible and visible alarm system. A separate parking space is allotted for the

differently abled guest that is nearest to the main building of the hotel block.Ramps are

built at the entrance to the lobby and to the room. The lift is situated just right across the

corridor where he can gain access to the Continental restaurant on the first floor. A unisex

Toilet for physically handicapped is being provided at the ground floor lobby level. The size

of the toilet is 52 sqft and consists of hand rail (@1mtr height) and other special features

and amenities that would cater to the needs of a differently abled guest.

1. AIR CONDITIONING SYSTEM – DAIKIN VRV IV

Daikin’s VRV IV systems integrate advanced technology to

provide comfort control with maximum energy efficiency and

reliabilty. Currently available in heat pump and heat recovery

configurations,VRV IV provides a solution for multi-family

residential to large commercial applications desiring heating or

cooling. The VRV IV is the first variable refrigerant flow (VRF)

system to be assembled in North America.

1.1. What’s new about VRV IV?

1. Optimized Installation with New Unit Ranges for low

total Life Cycle Cost (LCC)

Larger capacity single modules now range up to 14 tons.

Modules can be combined to provide up to 34 tons from

three modules on a single piping network, saving

installation cost by reducing piping and electrical

connections. Plus, system components allow flexibility to

handle future building changes while minimizing retrofit

VRV OUTDOOR UNIT

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requirements.

2. Energy Efficiency with Variable Refrigerant

Temperature (VRT)

VRV IV’s revolutionary Variable Refrigerant Temperature

control automatically adapts to the unique requirements of

your building and climate, significantly reducing seasonal

operational cost compared to VRV III. Customize your

operation between Automatic Mode, High Sensible Mode or

Basic Mode to suit the application’s needs. >See more about

VRT

3. Fast Installs mean Fast Commissions

VRV IV’s new commissioning tool enables designers to optimize system configurations to

take advantage of new system capabilities, as well as new products from Daikin. This

allows actual system settings to be optimized for comfort and energy savings from

installation, reducing commissioning time.

4. Ensure Peace of Mind with a Limited 10-Year Warranty*

VRV IV is the first Daikin VRV to be assembled in North America. A best-in-class warranty*

with 10-year compressor and parts limited warranty as standard ensures our confidence

in our new VRV IV. 

1.2. Overview of VRV IV Features.   

Total comfort solution for heating, cooling, ventilation and controls

Redesigned and optimized for total Life Cycle Cost (LCC)

Reduced install cost and increased flexibility as compared to VRV III with larger

capacity single modules up to 14 tons and system capacity up to 34 tons

Efficiency improved over VRV III by an average of 11% with IEER Values now up to

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Improved seasonal efficiency as compared to VRV III with automatic and

customizable Variable Refrigerant Temperature (VRT) climate tuning

Best-In-class warranty* with 10-year compressor and parts limited warranty as

standard

Reduced commissioning time vs. VRV III with VRV configurator software and

Graphical User Interface (GUI)

Design flexibility with long piping lengths up to 3,280 ft. total and 100 ft. vertical

separation between indoor units

Take advantage of Daikin’s unique zone and centralized controls

1.3. TECHNOLOGY

Daikin’s VRV IV systems integrate advanced technology to provide comfort control with

maximum energy efficiency and reliability. Currently available in heat pump and heat

recovery configurations, VRV IV provides a solution for multi-family residential to large

commercial applications desiring heating or cooling. The VRV IV is the first variable

refrigerant flow (VRF) system to be be assembled in North America.

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Variable Refrigerant Temperature

VRV – Constantly Evolving, Setting the Standard.

VRV IV combines a number of substantial improvements in system capability and function

compared to VRV III.

Larger capacity units now utilize new inverter compressors for all configurations. This

improves overall efficiency and allows the VRV IV to start with essentially no inrush power.

This is ideal for limiting demand expense and for solar installations or facilities that may

occasionally run on generator power, where a high amperage starting requirement is

difficult to meet.

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VRV IV now uses a four-sided coil that presents a greater heat exchange surface. While

allowing the same footprint for all unit sizes for ease of design, we have increased

efficiency through improved heat transfer on all sizes. This change has also enabled

increasing capacity in our standard modules, extending the range up to 34 tons on a single

network. Many applications have been simplified, as fewer units can be used to achieve

desired performance. Another added benefit to this is a reduction in system refrigerant

volume.

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1.4. FEATURES

Flexibility is everything

Large capacity range (6 – 34 ton), up to 64 indoor fan coil units on one system and

up to 200% connection ratio

Long piping length, up to 3,280’ total, with up to 100’ vertical separation

Wide range of indoor units, including additional “mini-split” units

Redesigned and optimized for low total Life Cycle Cost (LCC)

All inverter compressors in all model sizes

New configuration software allows full setup offsite with PC upload

10-year limited warranty* on compressor and parts is standard

* Complete warranty details available from your local dealer or at www.daikincomfort.com.

To receive the 10-year compressor and parts limited warranty, online registration must be

completed within 60 days of installation. Online registration is not required in California or

Quebec.

Environment

Efficient overall system performance, up to 28 IEER

Excellent heating performance, up to 4.20 COP

Variable Refrigerant Temperature control cycle provides improved seasonal

efficiency

Quieter than VRV III

Improved refrigerant leakage control

Reduced factory charge (refrigerant)

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Comfort

All-inverter technology

Continuous heating during oil return

Night time quiet mode

Backup function

Installation Advantages

Light modular design

Common footprint

Automatic charge function

Automatic test and self-diagnosis functions

Improved electrical and refrigerant piping connections

Automatic information storage

2. Sewage Treatment Plant

The quotation of STP has been confirmed with Diotech Systems and Projects,

Cochin which is one of the leading turnkey solutions providers of water and wastewater

treatment. The work is being executed according to the norms stated by the Pollution

Control Board. The waste water generated is being treated by SAFF METHOD The process

consists of Bar screen which removes all harmful materials like plastic cups, napkins

covers etc and various chemical treatments for safe land disposal. The sludge which is

resulting from the treatment is being pumped to the biogas plant which is again a

renewable source of energy. The treated water that is generated from the system can be

utilized for flushing, gardening etc.

2.1. Process Description

The treatment system consists of • Primary Treatment System• Biological Treatment System• Tertiary Treatment System

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2.1.1. Primary Treatment System

1. Sewage Collection A Septic Tank is provided for receiving the sewage from the building. The overflow

from the septic tank is directed to the collection cum equalization tank.

2.1.2. Biological Treatment System

1. Aerobic Treatment System

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The sewage from equalization tank is pumped to the aeration tank at a uniform

rate. The proposed Aerobic Treatment System shall have the following major components

a. Biological reactor (SAFF) b. Aeration System

1. Biological reactor (SAFF) The process employed in the biological reactor (SAFF) is extended aeration activated

sludge process. The waste water and active biomass is completely maintained in a

suspension and the MLSS is maintained at 3000-4000mg/L. The inlet of the aeration tank

is on the top with the waste water falling freely into the aeration tank. The outlet of the

aeration tank is connected to secondary settling tank. A recirculation of activated sludge is

maintained from bottom of the secondary settling tank to the aeration tank to maintain the

active biomass. The excess biomass will be directed to the Biogas Plant.

2. Aeration System The air will be supplied by providing Air Blower (Twin Lobe) in the aeration tank for

degradation of organics by micro-organisms. The Aeration System consists of 2 Nos. Air

Blowers. One Blower shall be on duty while the other shall be on stand by. The Blowers

shall be used for aeration inside aeration tank.

2.1.3. Tertiary Treatment System

The supernatant from the clarifier tank will be collected in the clarified water sump.

The treated water is pumped through the Pressure Sand Filter for removal of the remaining

suspended particles followed by Activated Carbon Filter for removal of remaining organic

and colors. Chlorination is provided in the clarified water tank for disinfection purposes

with the help of a variable discharge metering pump of capacity along with a dosing tank.

The treated water can be utilized for the non-contact applications like gardening, floor

wash, and flushing purpose.

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3. Water Treatment Plant

The treatment system consists of:

Collection and Aeration .

Chemical Treatment

Filtration System

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3.1. COLLECTION AND AERATION

The raw water is collected in the collection tank where a provision for Natural

Aeration is provided. Aeration will help to remove the organic wastes present in the water

if any and to precipitate and settle the iron content.

3.2. CHEMICAL TREATMENT SYSTEM

A mild dosage of Alum and Lime is done in to the collection tank. Lime is added for pH

neutralization purpose and Alum is added for coagulating the dissolved particles present in

the water and settling the same.

3.3. FILTRATION SYSTEM

There are four filtration units for the treatment. The water from the collection tank is

pumped through a Pressure Sand Filter for removing the remaining suspended particles, an

Activated Carbon Filter for removal of remaining organic and colors, a softener filter for

removing the hardness and finally through the RO membranes for removing the dissolved

solids and all other impurities. Backwash facility is provided for cleaning and maintenance

of the filters which is connected to the drain. The treated water is being stored in a treated

water tank, which can be further utilized for drinking, bathing and washing purpose.

3.4. Rain water harvesting

Kerala is a land of monsoons which give ample opportunity to harvest and reuse.

The rain water from the building is collected in a pit and reused in an herbal garden. There

are 2 pits at the amphitheatre where the rain water is collected and submerged in the

ground level area. Rain water harvesting system not only collects water within the

compound but also from the road and neighboring compounds. Instead of water flowing to

the sea, it is collected to corresponding pits within the compound to increase the ground

water level.

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4. Waste management

The proposal for waste management system has been sanctioned with No Waste. The

no fuel solid waste dispenser. No waste is an ecofriendly and economic solution for solid

waste disposal which runs on the principal of inceneration while addressing and solving

the major drawbacks of conventional incinerators like

a) Use of fuel and resultant environmental impacts

b) High initial investment

c) Recurring costs

d) Extensive space

‘NOWASTE’ works on Controlled Oxygen Rotating Technology incinerates solid waste by

combustion using atmospheric Oxygen, convert it into ash, heat, steam, and gas causing

minimal environmental impact. The manufacturing cost is comparatively very low, the fuel

free operation avoids recurring costs, and the compactness ensures minimum space for

installation.

Introduction of non CFC equipment for refrigeration and air conditioning

We are using air conditioners using VRF technology, which supports variable motor speed

and variable refrigerant flow rather than on/off operation. These features enable

substantial energy saving, allows individual units to heat or cool as required. Energy saving

upto 55% are predicted with this technology.

4.1 Bio Gas plant

Waste management involves a complex and wide range of occupational health and

safety relations. Waste management represents a reverse production process; the product

is removal of surplus materials. The original aim was simply to collect the materials, reuse

the valuable part of the materials and dispose of what remained at the nearest sites by eco

friendly and economically viable method.

Anaerobic digestion is a collection of processes by which microorganisms break down

biodegradable material in the absence of oxygen. The process is used for industrial or

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domestic purposes to manage waste and to produce fuels. The digestion process begins

with bacterial hydrolysis of the input materials. It is used as part of the process to treat

biodegradable waste and sewage sludge. As part of an integrated waste management

system, anaerobic digestion reduces the emission of landfill gas into the atmosphere.

Anaerobic digestion is widely used as a source of renewable energy. The process

produces a biogas, consisting of methane, carbon dioxide and traces of other contaminant

gases. This biogas can be used directly as fuel, in combined heat and power gas engines or

upgraded to natural gas quality bio methane. The nutrient rich digestate also produce can

be used as fertilizer.

4.1.1. Benefits and Advantages

In addition, biogas could potentially help to reduce global climate change. High levels

of methane are produce when manure is stored under anaerobic conditions. During storage

and when manure has been applied to the land, nitrous oxide is also produced as a

byproduct of the de nitrification process. Nitrous oxide (N2O) is 320 times more aggressive

than carbon dioxide and methane. i.e. the main advantages are it is a renewable source of

energy non polluting reduces landfills, cheaper technology, little capital investment,

reduces Green house effect.

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4.2. Incinerator

Global Incinerator- Role in Waste management

: Waste management is not that very easy to

maintain. In the modern world, the most popular

cities are being affected by constant threat by

pollution and waste gatherings. Though there are

recyclable materials piled up in the streets, useful

efforts have not been initiated by municipality or

corporation authorities. As a result, various

infections are spread over the country. All types of

inorganic waste has major role in this process.

Prevention is better than cure. Prevention in the early stage is less expensive. We have

developed a new concept to prevent air pollution by waste management, to safeguard our

ever green culture. It will be a global message in future. It is Global incinerator- that never

disturbs nature.

Global Incinerators are manufactured under strict supervision by professional

experts to ensure long term service. We have made maximum efforts to reduce the cost of

the equipment, though we have adopted the most advanced technology with international

standard.

Global Incinerators are easy to operate always on safe mode, as long as the instructions are

strictly followed as per the training by our technical experts.

4.2.1. Operational Instructions:

1. Always separate the waste materials from restricted materials like, plastic, glass

bottles, empty tin cans, spray bottles, fuel based items, thermocol etc. before each

operation.

2. Deposit wet and dry waste separately and burn the dry waste.

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3. Use, fuel jet before burning.

4. Light up the waste and switch on the primary air blower till the flame rises up.

5. Close the chamber door firmly once the flames are steady and switch on the

secondary air blower to transfer the fumes to scrubber and sludge tank.

6. Switch off the blowers when beep signal comes from panel board.

7. Do not collect ash while the burning in progress.

4.2.2. Salient Features of Global Incinerators

1. Triple Chamber Equipment with Wet & Dry burning facilities.

2. Wet Scrubber, Three Stage Filtration, Fuel dropper jet, Water level indication

device, Panel Board with beep signals.

3. Burns 90% of the waste into ash as a result less smoke emission.

4. Used 'A' grade refractory fire bricks to withstand temperature up to 1200*C.

5. Flame guard maintains combustion efficiency and prevents flame spreading into

emission pipe.

7. Rock wool prevents heat transmission over the body.

8. Drain pipes to transfer sediments frequently.

9. G-3 epoxy coated outer body, protects from influence of Weather damages

4.2.3. Parts of equipment:

1. Combustion Chamber: Refractory Fire Bricks, Cast Iron Hearth, Air Blower, Flame Guard ( Cast Iron- 12 mm thickness)

2. Master Emission Pipe: Double layered Cast Iron.

3. Wet waste chamber: Cast Iron grills with refractory fire bricks, drain pipes, diesel sprinkler jet

4. Scrubber: Wet scrubber technology

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5. Sludge Tank: Stacks up sediments.

6. Pipe connections to fill the tank as well as drain outlet

7. Panel Board facility for timely operations and clear signals

8. Three Stage Filters : Fabric Filter (FF), Bristle Filter (BF), Wire Filter(WF)

9. Ash Deposit tray : Poly Coated Tray

10. Foundation: Reinforced concrete foundation

11. Flame Guard : Anti Corrosive Layer coated G.I. Sheet

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4.2.4. Precautions:

1. Do not peep inside the chamber while the burning in progress.

2. Always use safety equipment like gloves, masks, glass and stirring rod.

3. Wear apron made of cotton materials.

4. Remove unburned materials from hearth before the second burning, to help sufficient air circulation

5. Drain the sludge tank and check water limit.

6. Beep signals indicate to switch off the air blowers.

7. Always keep the equipment surroundings clean. Do not stack up the waste nearby the equipment.

8. Clear the ash frequently, do not wait till it over flows.

9. Do not pour water inside the equipment, this will cause damage to the hearth.

10. Always entrust trained persons to operate the equipment.

4.2.5. Advantages:

1. Simple and safe operation

2. Burns 90 % of the waste, as a result, less smoke emission.

3. Useful for domestic, medical & industrial waste managements

4. Triple chamber helps to burn both wet and dry waste.

5. Required limited space for installation.

6. Only equipment available with 3 years warrantee and half yearly cleaning of accessories.

7. Low cost compared to others.

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5. Details of fire fighting measures/ Hydrants :

A fire fighting system is probably the most important of the building services, as

its aim is to protect human life and property, strictly in that order.

It consists of three basic parts:

A large store of water in tanks, either underground or on top of the building, called

fire storage tanks

A specialized pumping system,

A large network of pipes ending in either hydrants or sprinklers.

5.1. Fire Hydrant

A fire hydrant is a vertical steel pipe with an outlet, close to which two fire hoses

are stored. During a fire, firefighters will go to the outlet,

break open the hoses, attach one to the outlet, and manually

open it so that water rushes out of the nozzle of the hose. The

quantity and speed of the water is so great that it can knock

over the firefighter holding the hose if he is not standing in

the correct way. As soon as the fire fighter opens the hydrant,

water will gush out, and sensors will detect a drop in pressure

in the system. This drop in pressure will trigger the fire pumps to turn on and start

pumping water at a tremendous flow rate.

5.2. Sprinkler

A sprinkler is a nozzle attached to a network of pipes, and installed just below the

ceiling of a room. Every sprinkler has a small glass

bulb with a liquid in it. This bulb normally blocks the

flow of water. In a fire, the liquid in the bulb will

become hot. It will then expand, and shatter the

glass bulb, removing the obstacle and causing water

to spray from the sprinkler. The main difference

between a hydrant and a sprinkler is that a sprinkler

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will come on automatically in a fire. A fire hydrant has to be operated manually by trained

firefighters - it cannot be operated by laymen.

A sprinkler will usually be activated very quickly in a fire - possibly before the fire

station has been informed of the fire - and therefore is very effective at putting out a fire in

the early stages, before it grows into a large fire. For this reason, a sprinkler system is

considered very well at putting out fires before they spread and become unmanageable.

5.3. Fire storage tanks

The amount of water in the fire storage tanks is determined by the hazard level of

the project under consideration. Most building codes have at least three levels, namely,

Light Hazard (such as schools, residential buildings and offices)

Ordinary Hazard (such as most factories and warehouses),

High Hazard (places which store or use flammable materials like foam factories,

aircraft hangars, paint factories, fireworks factories).

The relevant building code lists which type of structure falls in each category.

The quantity of water to be stored is usually given in hours of pumping capacity. In system

with a capacity of one hour, the tanks are made large enough to supply the fire with water

for a period of one hour when the fire pumps are switched on. For example, building codes

may require light hazard systems to have one hour’s capacity and high hazard 3 or 4 hours

capacity.

The water is usually stored in concrete underground tanks. It is essential to ensure that this

store of water always remains full, so it must have no outlets apart from the ones that lead

to the fire pumps. These tanks are separate from the tanks used to supply water to

occupants, which are usually called domestic water tanks. Designers will also try and

ensure that the water in the fire tanks does not get stagnant and develop algae, which could

clog the pipes and pumps, rendering the system useless in a fire.

5.4. Fire pumping system

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Fire pumps are usually housed in a pump room very close to the fire tanks. The key

thing is that the pumps should be located at a level just below the bottom of the fire tank, so

that all the water in the tanks can flow into the pumps by gravity.

Like all important systems, there must be backup pumps in case the main pump

fails. There is a main pump that is electric, a backup pump that is electric, and a second

backup pump that is diesel-powered, in case the electricity fails, which is common. Each of

these pumps is capable of pumping the required amount of water individually - they are

identical in capacity.

There is also a fourth type of pump called a jockey pump. This is a small pump

attached to the system that continually switches on to maintain the correct pressure in the

distribution systems, which is normally 7 Kg/cm2 or 100 psi. If there is a small leakage

somewhere in the system, the jockey pump will switch on to compensate for it. Each jockey

pump will also have a backup.

The pumps are controlled by pressure sensors. When a fire fighter opens a

hydrant, or when a sprinkler comes on, water gushes out of the system and the pressure

drops. The pressure sensors will detect this drop and switch the fire pumps on. But the

only way to switch off a fire pump is for a fire fighter to do this manually in the pump room.

This is an international code of practice that is designed to avoid the pumps switching off

due to any malfunction in the control system.

The capacity of the pumps is decided by considering a number of factors, some of which

are:

Area covered by hydrants / standpipes and sprinklers

Number of hydrants and sprinklers

Assumed area of operation of the sprinklers

Type and layout of the building

5.5. The distribution system

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The distribution system consists of steel or galvanized steel pipes that are

painted red. These can be welded together to make secure joints, or attached with special

clamps. When running underground, they are

wrapped with a special coating that prevents

corrosion and protects the pipe.

There are basically two types of distribution systems

Automatic Wet systems are networks of pipes filled with water connected to the

pumps and storage tanks, as described so far.

Automatic Dry systems are networks of pipes filled with pressurized air instead of

water. When a fire fighter opens a hydrant, the pressurized air will first rush out. The

pressure sensors in the pump room will detect a drop in pressure, and start the water

pumps, which will pump water to the system, reaching the hydrant that the fire fighter is

holding after a gap of some seconds. This is done wherever there is a risk of the fire pipes

freezing if filled with water, which would make them useless in a fire.

Some building codes also allow manual distribution systems that are not connected to

fire pumps and fire tanks. These systems have an inlet for fire engines to pump water into

the system. Once the fire engines are pumping water into the distribution system, fire

fighters can then open hydrants at the right locations and start to direct water to the fire.

The inlet that allows water from the fire engine into the distribution system is called a

Siamese connection.

In high-rise buildings it is mandatory that each staircase have a wet riser, a vertical

fire fighting pipe with a hydrant at every floor. It is important that the distribution system

be designed with a ring main, a primary loop that is connected to the pumps so that there

are two routes for water to flow in case one side gets blocked.

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In more complex and dangerous installations, high and medium velocity water-spray

systems and foam systems (for hazardous chemicals) are used. The foam acts like an

insulating blanket over the top of a burning liquid, cutting off its oxygen. Special areas such

as server rooms, the contents of which would be damaged by water, use gas suppression

systems. In these an inert gas is pumped into the room to cut off the oxygen supply of the

fire.

When you design a fire fighting system, remember the following:

Underground tanks: water must flow from the municipal supply first to the

firefighting tanks and then to the domestic water tanks. This is to prevent

stagnation in the water. The overflow from the firefighting to the domestic tanks

must be at the top, so that the firefighting tanks remain full at all times. Normally,

the firefighting water should be segregated into two tanks, so that if one is cleaned

there is some water in the other tank should a fire occur.

It is also possible to have a system in which the firefighting and the domestic water

are in a common tank. In this case, the outlets to the fire pumps are located at the

bottom of the tank and the outlets to the domestic pumps must be located at a

sufficient height from the tank floor to ensure that the full quantity of water

required for fireghting purposes is never drained away by the domestic pumps. The

connection between the two tanks is through the suction header, a large diameter

pipe that connects the all the fire pumps in the pump room. Therefore there is no

need to provide any sleeve in the common wall between the two firefighting tanks.

The connection from each tank to the suction header should be placed in a sump; if

the connection is placed say 300mm above the tank bottom without a sump, then a

300mm high pool of water will remain in the tank, meaning that the entire volume

of the tank water will not be useable, to which the Fire Officer will object.

Ideally the bottom of the firefighting pump room should be about 1m below the

bottom of the tank. This arrangement ensures positive suction for the pumps,

meaning that they will always have some water in them.

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All pump rooms should without fail have an arrangement for floor drainage; pumps

always leak. The best way to do this is to slope the floor towards a sump, and install

a de-watering pump if the water cannot flow out by gravity.

In cases where there is an extreme shortage of space, one may use submersible

pumps for firefighting. This will eliminate the need for a firefighting pump room.

Create a special shaft for wet risers next to each staircase. About 800 x 1500 mm

should suffice. It is better to provide this on the main landing rather than the mid

landing, as the hoses will reach further onto the floor.

6. Security related features

The safety of the guest is of paramount importance. The security measures start as

soon as the guest checks inside the hotel where the guest is made to walk through the

metal detector and his baggage is run through the luggage scanner. The guest rooms are

secured with the lock and key card system from Godrej India. Each bedroom door is fitted

with peep hole and internal securing device. There is a provision of Safe in the wardrobe of

guest rooms to keep expensive items like jewelry, cash etc and is password protected and

accessible by the guest only. The security related features are also used for the internal

stakeholders where the punching machine is used at the security Time Office for employees

during Time In and Time out. There are CCTV cameras located in every nook and corner of

the hotels.

6.1. CC TV

Closed-circuit television, commonly known as CCTV, is a video monitoring system in

which all of the circuits are closed and all of the elements are directly connected. This is

unlike broadcast television where any receiver that is correctly tuned can pick up the

signal. CCTV may employ point to point (P2P), point to multipoint, or wireless links.

CCTV was first used in the 1940s by the company Siemens in Germany to observe

rockets launching. It went on to be installed in high-security locations such as banks, but

over the years CCTV has been used much more widely, most commonly associated with

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security and surveillance, and its prevalence has fuelled privacy concerns in many parts of

the world.

CCTV systems use strategically placed video cameras, to capture footage and feed it to

either a private network of monitors for real-time viewing, or to a digital video recorder

(DVR) for future reference.

Older CCTV systems used small, low-resolution black and white cameras and monitors

with no interactive capabilities. Modern CCTV systems display in full-colour and at high-

definition. This can be particularly helpful for facial recognition

which can be vital if analysis, investigation or legal proceedings are

a possibility.

CCTV cameras have the ability to zoom in and pan to track

action. Motion sensors can be used to automatically record when

there are signs of movement. This can be particularly useful for home security. Disc

indexing and time-stamping make locating and accessing recoded footage easier.

Night vision or Infra-red cameras can be used for applications

ranging from monitoring a sleeping baby, to carrying out surveillance in

the heart of combat zones.

A particular difficulty for large businesses is how to monitor

multiple camera feeds in a cost effective manner. Video analytics (or

video content analysis VCA) can help automate CCTV analysis recognising important

features such as license plates, or patterns of movement and allowing surveillance to focus

on potentially important events.

CCTV may be operated as part of a wider building management system, allowing

related systems such as access controls, alarms, sensors and lighting to be integrated. This

can permit greater control, achieve better responses and give improved flexibility.

28

CCTV images can be transmitted to a monitoring facility or can be accessed on

devices such as mobile phones, allowing responses to be directed remotely, such as police

or fire service action, or in some cases to permit access and de-activate alarms.

7. Elevator

An elevator or lift  is a type of vertical transportation that moves people or goods

between floors (levels, decks) of a building or other structure. Elevators are generally

powered by electric motors that either drive traction cables or counterweight systems like

a hoist, or pump hydraulic fluid to raise a cylindrical piston like a jack.

The key parts of an elevator are:

One or more cars (metal boxes) that rise up and down.

Counterweights that balance the cars.

An electric motor that hoists the cars up and down, including a braking system.

A system of strong metal cables and pulleys running between the cars and the

motors.

29

Various safety systems to protect the passengers if a cable breaks.

In large buildings, an electronic control system that directs the cars to the correct

floors using a so-called "elevator algorithm to ensure large numbers of people are

moved up and down in the quickest, most efficient way (particularly important in

huge, busy skyscrapers at rush hour). Intelligent systems are programmed to carry

many more people upward than downward at the beginning of the day and the

reverse at the end of the day.

The Gen2T.Nova system is the smart choice for 'green' buildings.

ReGen drive

A typical elevator includes three major components:

Machine elevator car counterweight

The counterweight is designed to

balance a half-loaded car. Electrical power is

generated when a heavily-loaded car travels

in a 'down' direction or a lightly-loaded car

travels in an 'up' direction (green area of

graph). With a non-regenerative drive the

energy generated is dissipated in a set of

resistors creating a waste heat load in the

building.

With a regenerative drive, the energy

generated is fed back into the building's grid

where it can be used by other loads

connected to the same network. The energy

consumed with a non-regenerative drive is

represented by the yellow area while with a

30

regenerative drive the energy consumed is just the difference between the yellow and

green areas.

The amount of energy savings due to regeneration depends on various system

parameters and configurations such as

Car load Speed Length of run Traffic pattern and System efficiency.

As the preferred choice for 'green' building initiatives, ReGen drives deliver substantial

energy savings while helping to meet or exceed established worldwide standards.

• Energy savings (up to 75%)

• Low harmonic distortion (typically below 5%) and reduced Radio Frequency Interference.

• Operational cost savings through reduced peak power demand and decreased energy consumption.

7.2. Environmental responsible

1. A 'green' machine

Neither the belts nor the gearless machine with sealed-for-life bearings require any

form of polluting lubricants. The low inertia gearless machine is equipped with a highly

efficient PM synchronous motor of radial construction.

The result is a machine which is up to:

50% more efficient than conventional geared machines.

10% more efficient than conventional gearless machines with induction

asynchronous motors.

15% more efficient than other machines with PM motors of axial construction

design.

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2. A gearless machine with a closed-loop VF drive increases passenger

comfort.

The gearless machine combined with a sophisticated load weighing device and a

closed loop variable frequency drive with vector control contribute to a smooth and quiet

ride. Furthermore, they result in outstanding stopping accuracy of within +1- 3mm at every

landing.

7.3. The Gen2TM Nova elevator offers exceptional levels of performance.

Faster operation

With adjustable acceleration

and deceleration rates, up to

0.6 m/s`. the Gen2T. Nova

elevator rapidly reaches its

nominal speed and

furthermore decelerates and

stops both smoothly and quickly.

7.4. While advanced security features demonstrate an absolute commitment to

both safety and reliability.

1. Safety features

For elevator users and service technicians.

• Door deterrent device

If the car is stopped between floors, a deterrent device prevents the car door from

opening. Hence a person cannot take the risk of exiting.

• Hoistway access detection

To protect a person entering the hoistway, a special safety feature prevents the elevator

from operating after a landing door has been opened.

• Rescue system

32

Battery-operated rescue system with electronic speed monitoring enables the safe

and fast rescue of trapped passengers in the event of a power failure.

Infra-red entrance protection

A screen of infrared beams acts as an invisible safety curtain. When an obstacle

breaks this screen, the sensitive 2D system detects it and immediately reopens the

doors.

Stopping accuracy

The belt's reduced stretch compared to conventional steel ropes together with a

closed loop VF control results in outstanding stopping accuracy (within +/-3 mm at

every landing).

Increased reliability

The PULSE' electronic system monitors the

status and integrity of the belt's steel cords 24/7d

providing advance notice of the need for replacement.

Not only does this improve their reliability and extend

then life but it also reduces the downtime required for inspection.

7.5. Standard features

1. Anti- nuisance car call protection

The elevator identifies that there is only a single passenger load in the car but more

than three or four calls have been registered, it would then cancel the calls. This feature

is to prevent unnecessary movement due to playful children.

2. Independent service (for duplex only)

When the independent key switch is turned on, all registered hall calls are

cancelled and the elevator responds only to car calls. No hall calls can be registered

during this service.

3. Overload device

33

When an overload is detected the car does not start and the doors remain open. The

elevator operation resumes only upon removal of the overload.

4. Nudging

If the doors are prevented from closing for a fixed period of time, a buzzer is activated

and the doors begin to close at a reduced speed.

5. Emergency firemen's service

This feature automatically places the car at the designated return landing with the

doors fully open. The fireman can then enter and take control of the elevator.

6. Emergency car light unit

An automatically rechargeable emergency power supply will switch on i ipon failure

of the normal lighting supply.

7. Infrared curtain door protection

Entrance protection system forms a safety net across the effective entrance area with

invisible Infrared beams that are able to detect passengers and objects in the path of

closing doors, within a fraction of second. Therefore, should a passenger enter or exit the

elevator just when the doors close, the system instantaneously reopens the elevator doors

allowing, the passengers to enter or exit freely.

Due to its design superiority even if a single beam is interrupted, the elevator door

opens automatically and remains open until the passenger clears the door way.

8. Door time protection

If the car door does not close completely within an adjustable time after the door

close command, the elevator will enter the DTC mode. remove itself from group operation.

Halt calls will be assigned to other elevators in the group. Open its doors and sound the

buzzer in the car operating pane. Attempt closing the doors again. After three unsuccessful

retries, the car will shut down with its doors open, Pending car calls will be cleared_

34

9. Emergency alarm button

The emergency alarm hell located at the ground floor / lobby will be activated by

pressing the alarm button in the car operating panel, the device is powered by battery.

10.Extra door time of lobby & parking

The lobby door time is normally longer than the time at other landings to allow extra

passenger traffic at the lobby. Door timing is adjustable to suit the needs of the building:

11.Door open / close button

Door open / close button in the car operating panel permits independent. opening I

closing of automatic door, and to keep it open / dosed by constant pressure.

12.Manual rescue operation

The rescue of c.;eople trapped within the car is carried out by the manual inspection

rescue device. It allows the movement of the car to the closest floor.

13.Belt inspection device

Reliability and safety are further enhanced with Otis' PULSE Electronic system

which continually monitors the status of the belt's steel cords 24h/7d. Contrary to current

visual inspections of conventional steel ropes, the Otis PULSE" system automatically

detects and indicates through LED. This feature helps Otis technicians to monitor the

quality of the belt cord and greatly enhances the reliability of the inspection.

8. SOLAR THERMAL POWER PLANT

35

Solar thermal energy (STE) is a form of energy and a technology for harnessing solar

energy to generate thermal energy  or electrical energy for use in industry, and in the

residential and commercial sectors.

Solar thermal power plants use the sun's rays to heat a fluid to high temperatures. The

fluid is then circulated through pipes so that it can transfer its heat to water and produce

steam. The steam is converted into mechanical energy in a turbine, which powers a

generator to produce electricity.

Solar thermal power generation works essentially the same as power generation using

fossil fuels, but instead of using steam produced from the combustion of fossil fuels, the

steam is produced by heat collected from sunlight. Solar thermal technologies use

concentrator systems to achieve the high temperatures needed to produce steam.

8.1. Types of solar thermal power plants

There are three main types of solar thermal power systems:

Parabolic trough

Solar dish

Solar power tower

8.1.1. Parabolic troughs

Parabolic troughs are used in the longest operating solar thermal power facility in the

world, which is located in the Mojave Desert in California. The Solar Energy Generating

System (SEGS) has nine separate plants. The first plant, SEGS 1, has operated since 1984,

and the last SEGS plant that was built, SEGS IX, began operation in 1990. The SEGS facility is

one of the largest solar thermal electric power plants in the

world.

A parabolic trough collector has a long parabolic-shaped

reflector that focuses the sun's rays on a receiver pipe located at

the focus of the parabola. The collector tilts with the sun as the

36

sun moves from east to west during the day to ensure that the sun is continuously focused on the

receiver.

Because of its parabolic shape, a trough can focus the sun from 30 times to 100 times

its normal intensity (concentration ratio) on the receiver pipe located along the focal line of

the trough, achieving operating temperatures higher than 750°F.

The solar field has many parallel rows of solar parabolic trough collectors aligned on a

north-south horizontal axis. A working (heat transfer) fluid is heated as it circulates

through the receiver pipes and returns to a series of heat exchangers at a central location.

Here, the fluid circulates through pipes so it can transfer its heat to water to generate high-

pressure, superheated steam. The steam is then fed to a conventional steam turbine and

generator to produce electricity. When the hot fluid passes through the heat exchangers, it

cools down, and is then recirculated through the solar field to heat up again.

The power plant is usually designed to operate at full power using solar energy alone,

given sufficient solar energy. However, all parabolic trough power plants can use fossil fuel

combustion to supplement the solar output during periods of low solar energy.

8.1.2. Solar dishes

Solar dish/engine systems use concentrating solar collectors that track the sun, so they

always point straight at the sun and concentrate the solar energy at the focal point of the

dish. A solar dish's concentration ratio is much higher than a solar trough's concentration

ratio, and it has a working fluid temperature higher than 1,380°F. The power-generating

equipment used with a solar dish can be mounted at the focal point of the dish, making it

well suited for remote operations or, as with the solar trough, the energy may be collected

from a number of installations and converted into electricity at a

central point. The engine in a solar dish/engine system converts heat

to mechanical power by compressing the working fluid when it is cold,

heating the compressed working fluid, and then expanding the fluid

through a turbine or with a piston to produce work. The engine is

coupled to an electric generator to convert the mechanical power to electric power.

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8.1.3. Solar power tower

A solar power tower, or central receiver, generates electricity from sunlight by

focusing concentrated solar energy on a tower-mounted heat exchanger (receiver). This

system uses hundreds to thousands of flat, sun-tracking mirrors called heliostats to reflect

and concentrate the sun's energy onto a central receiver tower. The energy can be

concentrated as much as 1,500 times that of the energy coming in from the sun.

Energy losses from thermal-energy transport are minimized because solar energy is

being directly transferred by reflection from the heliostats to a single receiver, rather than

being moved through a transfer medium to one central location, as with parabolic troughs.

Power towers must be large to be economical. This is promising technology for large-

scale grid-connected power plants. The U.S.

Department of Energy, along with a number of

electric utilities, built and operated a

demonstration solar power tower near Barstow,

California, during the 1980s and 1990s.

8.2. Technology

Most techniques for generating electricity from heat need high temperatures to achieve

reasonable efficiencies. The output temperatures of non-concentrating solar collectors are

limited to temperatures below 200°C. Therefore, concentrating systems must be used to

produce higher temperatures. Due to their high costs, lenses and burning glasses are not

usually used for large-scale power plants, and more cost-effective alternatives are used,

including reflecting concentrators.

The reflector, which concentrates the sunlight to a focal line or focal point, has a

parabolic shape; such a reflector must always be tracked. In general terms, a distinction can

be made between one-axis and two-axis tracking: one-axis tracking systems concentrate

the sunlight onto an absorber tube in the focal line, while two-axis tracking systems do so

onto a relatively small absorber surface near the focal point (see Figure 1).

38

FIGURE 1. Concentration of sunlight using (a) parabolic trough collector (b) linear Fresnel collector (c) central

receiver system with dish collector and (d) central receiver system with distributed reflectors

The theoretical maximum concentration factor is 46,211. It is finite because the sun

is not really a point radiation source. The maximum theoretical concentration temperature

that can be achieved is the sun’s surface temperature of 5500°C; if the concentration ratio

is lower, the maximum achievable temperature decreases. However, real systems do not

reach these theoretical maxima. This is because, on the one hand, it is not possible to build

an absolutely exact system, and on the other, the technical systems which transport heat to

the user also reduce the receiver temperatures. If the heat transfer process stops, though,

the receiver can reach critically high temperatures.

39

8.2.1. Parabolic Trough Power Plants

Parabolic trough power plants are the only type of solar thermal power plant

technology with existing commercial operating systems until 2008. In capacity terms, 354

MWe of electrical power are installed in California, and a plenty of new plants are currently

in the planning process in other locations.

FIGURE . Schematic of a concentrated solar thermal trough power plant with thermal

storage

The parabolic trough collector consists of large curved mirrors, which concentrate the

sunlight by a factor of 80 or more to a focal line. Parallel collectors build up a 300–600

metre long collector row, and a multitude of parallel rows form the solar collector field. The

one-axis tracked collectors follow the sun.

The collector field can also be formed from very long rows of parallel Fresnel collectors. In

the focal line of these is a metal absorber tube, which is usually embedded in an evacuated

glass tube that reduces heat losses. A special high-temperature, resistive selective coating

additionally reduces radiation heat losses.

40

In the Californian systems, thermo oil flows through the absorber tube. This tube heats up

the oil to nearly 400°C, and a heat exchanger transfers the heat of the thermal oil to a water

steam cycle (also called Rankine cycle). A feedwater pump then puts the water under

pressure. Finally, an economizer, vaporizer and superheater together produce superheated

steam. This steam expands in a two-stage turbine; between the high-pressure and low-

pressure parts of this turbine is a reheater, which heats the steam again. The turbine itself

drives an electrical generator that converts the mechanical energy into electrical energy;

the condenser behind the turbine condenses the steam back to water, which closes the

cycle at the feedwater pump.

It is also possible to produce superheated steam directly using solar collectors. This makes

the thermo oil unnecessary, and also reduces costs because the relatively expensive thermo

oil and the heat exchangers are no longer needed. However, direct solar steam generation

is still in the prototype stage.

8.2.2. Guaranteed Capacity

In contrast to photovoltaic systems, solar thermal power plants can guarantee

capacity (see Figure 2). During periods of bad weather or during the night, a parallel, fossil

fuel burner can produce steam; this parallel burner can also be fired by climate-compatible

fuels such as biomass, or hydrogen produced by renewables. With thermal storage, the

solar thermal power plant can also generate electricity even if there is no solar energy

available.

A proven form of storage system operates with two tanks. The storage medium for

high-temperature heat storage is molten salt. The excess heat of the solar collector field

heats up the molten salt, which is pumped from the cold to the hot tank. If the solar

collector field cannot produce enough heat to drive the turbine, the molten salt is pumped

back from the hot to the cold tank, and heats up the heat transfer fluid. Figure 3 shows the

principle of the parabolic trough power plant with thermal storage.

8.2.3. Solar Thermal Tower Power Plants

41

In solar thermal tower power plants, hundreds or even thousands of large two-axis

tracked mirrors are installed around a tower. These slightly curved mirrors are also called

heliostats; a computer calculates the ideal position for each of these, and a motor drive

moves them into the sun. The system must be very precise in order to ensure that sunlight

is really focused on the top of the tower. It is here that the absorber is located, and this is

heated up to temperatures of 1000°C or more. Hot air or molten salt then transports the

heat from the absorber to a steam generator; superheated water steam is produced there,

which drives a turbine and electrical generator, as described above for the parabolic trough

power plants. Only two types of solar tower concepts will be described here in greater

detail.

8.2.4. Open Volumetric Air Receiver Concept

The first type of solar tower is the open volumetric receiver concept (see Figure 4a).

A blower transports ambient air through the receiver, which is heated up by the reflected

sunlight. The receiver consists of wire mesh or ceramic or metallic materials in a

honeycomb structure, and air is drawn through this and heated up to temperatures

between 650°C and 850°C. On the front side, cold, incoming air cools down the receiver

surface. Therefore, the volumetric structure produces the highest temperatures inside the

receiver material, reducing the heat radiation losses on the receiver surface. Next, the air

reaches the heat boiler, where steam is produced. A duct burner and thermal storage can

also guarantee capacity with this type of solar thermal power plant.

8.2.5. Pressurized Air Receiver Concept

The volumetric pressurized receiver concept (see Figure 4b) offers totally new

opportunities for solar thermal tower plants. A compressor pressurizes air to about 15 bar;

a transparent glass dome covers the receiver and separates the absorber from the

environment. Inside the pressurized receiver, the air is heated to temperatures of up to

1100°C, and the hot air drives a gas turbine. This turbine is connected to the compressor

and a generator that produces electricity. The waste heat of the gas turbine goes to a heat

boiler and in addition to this drives a steam-cycle process. The combined gas and steam

42

turbine process can reach efficiencies of over 50%, whereas the efficiency of a simple

steam turbine cycle is only 35%. Therefore, solar system efficiencies of over 20% are

possible.

FIGURE 4. Schematic of two types of solar thermal tower power plant, showing (a) an

open volumetric receiver with steam turbine cycle and (b) a pressurized receiver

with combined gas and steam turbine cycle

8.2.6. Comparing Trough and Tower

In contrast to the parabolic trough power plants, no commercial tower power plant

exists at present. However, prototype systems – in Almería, Spain, in Barstow, California,

43

US, and in Rehovot, Israel – have proven the functionality of various tower power plant

concepts.

The minimum size of parabolic trough and solar tower power plants is in the range of

10 MWe. Below this capacity, installation and O&M costs increase and the system efficiency

decreases so much that smaller systems cannot usually operate economically. In terms of

costs, the optimal system size is in the range of 50–200 MWe.

8.2.7. Dish-Stirling Systems

So-called Dish–Stirling systems can be used to generate electricity in the kilowatts

range. A parabolic concave mirror (the dish) concentrates sunlight; the two-axis tracked

mirror must follow the sun with a high degree of accuracy in order to achieve high

efficiencies. In the focus is a receiver which is heated up to 650°C. The absorbed heat drives

a Stirling motor, which converts the heat into motive energy and drives a generator to

produce electricity. If sufficient sunlight is not available, combustion heat from either fossil

fuels or biofuels can also drive the Stirling engine and generate electricity. The system

efficiency of Dish–Stirling systems can reach 20% or more. Some Dish–Stirling system

prototypes have been successfully tested in a number of countries. However, the electricity

generation costs of these

systems are much higher than

those for trough or tower

power plants, and only series

production can achieve further

significant cost reductions for

Dish–Stirling systems.

8.2.8. Solar Chimney Power Plants

All three technologies described above can only use direct normal irradiance.

However, another solar thermal power plant concept – the solar chimney power plant –

converts global irradiance into electricity. Since chimneys are often associated negatively

44

with exhaust gases, this concept is also known as the solar power tower plant, although it is

totally different from the tower concepts described above. A solar chimney power plant has

a high chimney (tower), with a height of up to 1000 metres, and this is surrounded by a

large collector roof, up to 130 metres in diameter, that consists of glass or resistive plastic

supported on a framework (see artist’s impression). Towards its centre, the roof curves

upwards to join the chimney, creating a funnel.

The sun heats up the ground and the air underneath the collector roof, and the

heated air follows the upward incline of the roof until it reaches the chimney. There, it

flows at high speed through the chimney and drives wind generators at its bottom. The

ground under the collector roof behaves as a storage medium, and can even heat up the air

for a significant time after sunset. The efficiency of the solar chimney power plant is below

2%, and depends mainly on the height of

the tower, and so these power plants can

only be constructed on land which is

very cheap or free. Such areas are

usually situated in desert regions.

However, the whole power plant

is not without other uses, as the outer

area under the collector roof can also be

utilized as a greenhouse for agricultural

purposes. As with trough and tower plants, the minimum economical size of solar chimney

power plants is also in the multi-megawatt range.

9. WIND POWER GENERATION

The wind is a source of free energy which has been used since ancient times in

windmills for pumping water or grinding flour. The technology of high power, geared

transmissions was developed centuries ago by windmill designers and the fantail wheel for

45

keeping the main sales pointing into the wind was one of the world's first examples of

an automatic control system .

 

9.1. Fixed Speed Wind Turbine Generators

 

A typical fixed speed system employs a rotor with three variable pitch blades which

are controlled automatically to maintain a fixed rotation speed for any wind speed. The

rotor drives a synchronous generator through a gear box and the whole assembly is housed

in a nacelle on top of a substantial tower with massive foundations requiring hundreds of

cubic metres of reinforced concrete.

Fixed speed systems may however suffer excessive mechanical stresses. Because they are

required to maintain a fixed speed regardless of the wind speed, there is no "give" in the

mechanism to absorb gusty wind forces and this results in high torque, high stresses and

excessive wear and tear on the gear box increasing maintenance costs and reducing service

life. At the same time, the reaction time of

these mechanical systems can be in the range

of tens of milliseconds so that each time a burst

of wind hits the turbine, a rapid fluctuation of

electrical output power can be observed.

Furthermore, variable speed wind turbines can

capture 8-15% more of the wind's energy than

constant speed machines. For these reasons, variable speed systems are preferred over

fixed speed systems. See more about the properties of synchronous generators.

9.2. Variable Speed Wind Turbine Generators

A variable speed generator is better able to cope with stormy wind conditions because

its rotor can speed up or slow down to absorb the forces when bursts of wind suddenly

increase the torque on the system. The electronic control systems will keep the generator's

output frequency constant during these fluctuating wind conditions.

46

 

Synchronous Generator with In-Line Frequency Control

Rather than controlling the turbine rotation speed to obtain a fixed frequency

synchronised with the grid from a synchronous generator, the rotor and turbine can be

run at a variable speed corresponding to the prevailing wind conditions. This will

produce a varying frequency output from the generator synchronised with the drive

shaft rotation speed. This output can then be rectified in the generator side of an AC-

DC-AC converter and the converted back to AC in an inverter in grid side of the

converter which is synchronised with the grid frequency. See following diagram. The

grid side converter can also be used to provide reactive power (VArs) to the grid for

power factor control and voltage regulation by varying the firing angle of the thyristor

switching in the inverter and thus the phase of the output current with respect to the

voltage. See an explanation and more details of why reactive power is needed in the

section about Power Quality and Voltage Support as used in the utility grid.

 

 

The range of wind speeds over which the system can be operated can be extended and

mechanical safety controls can be incorporated by means of an optional speed control

system based on pitch control of the rotor vanes as used in the fixed speed system

described above.

47

One major drawback of this system is that the components and the electronic control

circuits in the frequency converter must be dimensioned to carry the full generator

power. The doubly fed induction generator DFIG overcomes this difficulty.

 

9.3. Doubly Fed Induction Generator - DFIG

DFIG technology is currently the preferred wind power generating technology. The

basic grid connected asynchronous induction generator gets its excitation current from

the grid through the stator windings and has limited control over its output voltage and

frequency. The doubly fed induction generator permits a second excitation current

input, through slip rings to a wound rotor permitting greater control over the generator

output.

The DFIG system consists of a 3 phase wound rotor generator with its stator windings

fed from the grid and its rotor windings fed via a back to back converter system in a

bidirectional feedback loop taking power either from the grid to the generator or from

the generator to the grid. See the following diagram.

 

 

Generator Operating Principle

The feedback control system monitors the stator output voltage and frequency and

provides error signals if these are different from the grid standards. The frequency

48

error is equal to the generator slip frequency and is equivalent to the difference

between the synchronous speed and the actual shaft speed of the machine.

The excitation from the stator windings causes the generator to act in much the

same way as a basic squirrel cage or wound rotor generator, (See more about the

properties of induction generators and how they work.). Without the additional

rotor excitation, the frequency of a slow running generator will be less than the grid

frequency which provides its excitation and its slip would be positive. Conversely if

it was running too fast the frequency would be too high and its slip would be

negative.

The rotor absorbs power from the grid to speed up and delivers power to the grid in

order to slow down. When the machine is running synchronously the frequency of

the combined stator and rotor excitation matches the grid frequency, there is no slip

and the machine will be synchronised with the grid.

 

Grid Side Converter - GSC : Carries current at the grid frequency. It is an AC to

DC converter circuit used to provide a regulated DC voltage to the inverter in the

machine side converter (MSC). It is used maintain a constant DC link voltage. A

capacitor is connected across the DC link between the two converters and acts

as an energy storage unit. The grid side converter is used to maintain a constant

DC link voltage. In the opposite direction the GSC invereter delivers power to

the grid with the grid regulated frequency and voltage.

As with the in-line converter described above, by adjusting the timing of the GSC

inverter switching, the GSC converter also provides variable reactive power

output to counterbalance the reactive power drawn from the grid enabling

power factor correction as in the in-line frequency control system described

above.

 

Machine Side Converter - MSC: Carries current at slip frequency. It is an DC to

AC inverter which is used to provide variable AC voltage and frequency to the

rotor to control the torque and speed of the machine.

49

When the generator is running too slowly, its frequency will be too low so that it

is essentially motoring. The machine side converter takes DC power from the DC

link and provides AC output power at the slip frequency to the rotor to eliminate

its motoring slip and thus increase its speed. If the rotor is running too fast

causing the generator frequency to be too high, the MSC extracts AC power from

the rotor at the slip frequency causing it to slow down, reducing the generator

slip, and converts the rotor output to DC passing it through the DC link to the

GSC where it is converted to the fixed grid voltage and frequency and is inserted

into the grid.

9.4. Domestic Wind Turbine Installations

In a typical domestic system the wind turbine is coupled directly to a three phase

asynchronous permanent magnet AC generator mounted on the same shaft. To save on  

capital costs, domestic installations do not have variable pitch rotor blades so the rotor

speed varies with the wind speed. The generator output voltage and frequency are

proportional to the rotor speed and the current is proportional to the torque on the shaft.

The output is rectified and fed through a buck-boost regulator to an inverter which

generates the required fixed amplitude and frequency AC voltage.

10. GREEN CERTIFICATE

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A Green Certificate - terminology predominantly used in Europe but now

becoming more widespread globally - are a tradable commodity proving that certain

electricity is generated using renewable energy sources. Typically one certificate

represents generation of 1 Megawatt hour of electricity. What is defined as "renewable"

varies from certificate trading scheme to trading scheme. Usually, at least the following

sources are considered as renewable:

Wind (often further divided into onshore and offshore)

Solar (often further divided into photovoltaic and thermal)

Wave (often further divided into onshore and offshore) and tidal (often further divided

into onshore and offshore)

Geothermal

Hydro (often further divided into small - microhydro - and large)

Biomass (mainly biofuels, often further divided by actual fuel used).

Green certificates represent the environmental value of renewable energy

generated. The certificates can be traded separately from the energy produced. Several

countries use green certificates as a mean to make the support of green electricity

generation closer to a market economy instead of more bureaucratic investment support

and feed-in tariffs. Such national trading schemes are in use in e.g. Poland, Sweden, the UK,

Italy, Belgium (Wallonia and Flanders), and some US states.

Once in the grid, renewable energy is impossible to separate from the

conventionally generated energy. This makes purchasing of a green certificate equal to

purchasing a claim, that the certificate owner consumed energy from the renewable

portion of the whole energy in the grid. Therefore certificate purchase does not affect how

much renewable energy was actually generated - only how it was distributed.

In contrast to CO2e-Reduction certificates, e.g. AAU's or CER's under the UNFCC, which can

be exchanged worldwide, Green Certificates cannot be exchanged/traded between e.g.

Belgium and Italy, let alone the USA and the EU member States.

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