International Journal of Research ISSN NO:2236-6124ijrpublisher.com/gallery/146-january-2019.pdf · waste heat and can help reduce needed energy and thermal contamination. Many adsorption

A VALIDATION OF THE CFD MODELS WITH THE DATA AVAILABLE IN THE

PRACTICAL APPROACH FOR AIR CONDITIONER

B. Pavan Kumar Goud Research Scholar

Shri JJT University

Rajasthan

[email protected]

S.Chakradhara Goud Prof. & Principal

Moghal College of Engineering &

Technology, Hyderabad

[email protected]

ABSTRACT

Chlorofluorocarbon and hydro chlorofluorocarbon

refrigerants are widely utilized in conventional

cooling systems. All these refrigerants hasten the

depletion of the planet's ozone layer.

Consequently, adsorption air-conditioning

attracted much attention lately as an alternate

solution because of its benefit of ecological

friendliness. This method is powered by solar or

waste heat and can help reduce needed energy and

thermal contamination. Many adsorption pairs are

studied. Zeolite--water as a functioning adsorption

set has been broadly utilized in auto adsorption

cooling methods. This set was power driven by

exhaust gases generated by the engine because of

its high temperature. Silica gelwater set is also

largely utilized in auto adsorption methods. Waste

heat has powered it from water in the engine

because of its comparatively low temperature.

Results reveal that this technology helps in raising

engine performance and reduce pollution from

engines. Alterations in adsorption cooling systems

are yet needed. Main hindrance that prevents

adsorption technology's development is its

reduced performance when compared with

traditional vapor compression technologies that

are mechanical.

This researchprovides the features of an advanced

cooling system for a first assessment of its

functionality, in addition to its airconditioning unit

of a truck’scabin through a cycle, acquired using a

developed vehicle-engine- cooling system version.

The advanced cooling system contains a water-

zeolite adsorption-desorptionunit, which uses the

waste heat generated by the engine to generate the

cooling effect of the automobile cabin. The

developed worldwide model is totally dynamic and

is ready to: replicate the performance of the engine

via a regular driving cycle, assess the waste heat

available inthe engine hydraulic loop; compute the

successive operation of an adsorption-desorption

system, compute the condensed water each cycle,

the warming effect generated in the evaporator,

and in the end, the humidity and temperature

development of the atmosphere within the cabin.

Experimental data confirmed the model.

1.0 INTRODUCTION

There is a fast progress in energy usage in

the past couple of decades. So there's

been a need to cut the energy used by

various purposes in daily life. Nano

particles are utilized to pull the interest

lately for the reason of their diverse uses.

Addition of alloy or non-metal oxides into

a base fluid results in a distinct working

fluid known as NANO FLUID. Addition

of Nano particles contribute to change in

both transportation and thermal properties

of fluid. In a conventional ac system,

there'll be particular quantity of

lubricating oil that's carried in

compressor by the refrigerant. So,

particular volume of lubricating oil flows

together with the refrigerant in the air

conditioning unit. If the lubricating oil is

less soluble in the refrigerant, then there’s

a drawback of gathering of lubricating oil

at the condenser.

If the lubricating oil is more soluble in the

refrigerant, refrigerant flows out all of the

lubricating fluid from the compressor and

there's a danger of corrosion in the

compressor. Thus, for the appropriate

performance of the appliance using the

given refrigerant and lubricating oil, they

should be suitable with one another. For

the refrigerant and lubricating oil to be

suitable, polarity of the lubricating oil and

also the refrigerant should be same. This

guarantees optimum solubility of

lubricating oil from the refrigerant. Nano

particles that are mixed in to the

lubricating oil blocks the surface thereby,

decreasing the sliding friction in between

the surfaces. Blocking of the surface

International Journal of Research

Volume VIII, Issue I, January/2019

ISSN NO:2236-6124

Page No:1161

coarseness resulted in reduction of the

sweltering heat transfer features.

Addition of Nano particles also found to

improve the acute heat flux of this

refrigerant. Literature review indicates that

Nano fluids thermal conductivity is

significantly higher when compared to the

base fluid. Additionally, viscosity of Nano

fluid is higher when compared with the

base fluid. All of these are few of the

advantages of Nano particles. Nano

particles have few disadvantages as well.

There's a drawback of accumulation

of Nano particles in compressor if it

isn't spread well in the oil. In the

event the Nano particles not dispensed

appropriately, there's a threat of their

intervention with surroundings.

Graph T-S (Temperature-Entropy)

diagram of R-410a

Nano particles are known to inhibit the

plant growth. They're carcinogenic

and therefore appropriate care must be

taken in handling them. Economic issues

in terms of use of Nano particles should

also be well thought-out as they're

rather expensive. There fragrant R-410a

has been used in the air-

conditioningsetupfortesting.Therefrigerant

R-410aisisotropicindicatingthat the

variation in the temperature phase wont

remain continual whereas for traditional

refrigerants it is constant. Temperature of

the refrigerant (R-410a) goes down during

the change of phase.

2.0 LITERATURE REVIEW

Dhiraj M. Ghose et al (2015)Vapour

adsorption cooling system doesn't need

any kind of external power such as

electrical or mechanical force for its

functioning. The waste heat coming out of

the exhaust of an automotive engine is

used in powering the adsorption cooling

system there by producing the cooling

effect. Parameters affecting the

functioning of the chilling system are

widely addressed. Also, the use of

refrigerant and adsorbent pair in the

experimental approach of system is

researched and discussed in this review

paper.

Benrajesh, P et al (2012) this article's

purpose is to model and construct a bio-

friendly air-conditioner, using adsorption

system with the content of 15% calcium

carbide present in the water. Aluminum

sheets are utilized in forming three similar

tunnels for the passage of airflow for

processing. For cooling the surroundings,

heat produced in the dairy unit procedure

that is sterilizing is reutilized. This gear is

designed and the evaluation is performed

to measure SCP, the COP and the power of

cooling. Heat exchangers are created; it’s

Performance and Parameters are measured

and were equated to the previous designs.

It's noticed that the fresh adsorption chiller

will create the coefficient of operation of

chiller as 1.068; the particular refrigeration

power of 10.66 (W/Kg); along with the

cooling ability of 3.2 KW. From the

opening temperature of 29°c to the

required cooling temperature of 24°c, the

time require for this system is in between 0

to 15 minutes.

Shahid Imam, Md et al (2013) Transportation is a very crucial aspect in

modern era. The effective way of using of

air conditionings has been growing more

challenging day by day.In the present,

design of AC is carried for a Volvo bus

with a system made up of five elements:

an evaporator, a blower, a condenser, an

opening cylinder and a collector. R-134a



ISSN NO:2236-6124

Page No:1162

can be used as refrigerant by considering

the parameters.

Shrivastava, A. P et al (2016) Car cooling

(AAC) framework give straightforwardly

and in a roundabout way to the issues of

global warming. It also affects the ozone

layer. The effects of ac systems on

environment can be lowered by the

utilization of other eco-friendly

refrigerants that are detrimental to the

atmosphere. Since propane gas has

minimal effect on global warming and no

ozone depleting substance, use of propane

(R290) as a refrigerant is a fantastic

opportunity to make eco-friendly way for

your AAC. The discussion of the paper is

to get theoretical evaluation purpose,

thermodynamic analysis of conventional

Vapor Compression Refrigeration System

(VCRS) has been finished and a MS-Excel

spreadsheet was created to appraise

performance parameters such as cooling

impact, compressor feature, and

coefficient of performance, mass stream

rate, and volumetric refrigerating limit and

power each a lot of refrigeration. For

evaluation purpose, an experimental

arrangement was established using

elements relative with propane and

instrumented. Analysis indicates that

properties of the physical properties along

with HC-290 are more exceptional in

comparison to making it likely for

replacement. The outcome indicates that

the propane does have refrigerating effect,

slightly COP but higher compressor work

that could be further reduced by designing

compressor to be used by propane. Hence,

propane might be efficiently used within

AAC system.

Toshihisa Kondo et al (2011)In the

future, the market for electric and hybrid

vehicles is anticipated to extend against a

background of environmental security and

CO2 emission controls that were

tightened. This report clarifies the

inspection of a warmth siphon cooling

framework that uses vitality in the

atmosphere to heat the car cabin. This

method reduces electricity consumption by

20% to 60% when compared with current

systems, when applied to hybrid and

electric vehicles.

3.0 METHODOLOGY

Introduction to air conditioner for

automotive application

It had been supposed that the thermal loads

present in cabin comprises of loads from

solar irradiation, passengers' body heats,

heat that are in the automobile body and

also atmosphere conduct (chilling and

dehumidification). For simplicity, the solar

irradiation was supposed constant in 1

kW/m2 together with the exposed auto

window area has been 2 m2.All these are

Normal for a sedan car during afternoon

climate in Singapore. The window glass

has to have a transmissivity of 0.75. There

were four passengers in the vehicle, of

which each individual was emitting around

120W of heat. The automobile body had a

thermal conductivity of 1.257 W/m2. K of

70°C and area of 3 m2. Also 0.06 Kg/s

was the air flow rate.

Figure Schematic Diagram of

Automotive Air Conditioning System



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To permit the system to work over a

selection of requirements, the compressor

is turned off and on based upon the

refrigerant weight. The blower is closed

off at whatever pointthe weight in the

evaporator falls beneath the esteem that is

3 chosen to guarantee condensate doesn't

solidify the evaporator. Following the

blower stop, there will bear a weight

awkwardness all through the extension

valve which may constrain refrigerant to

stream out of condenser to the evaporator.

Since the evaporator meddles with all the

refrigerant, its weight increments.

Compressor is turned off and on in such a

fashion. As the compressor is belt driven

apparatus paired to the engine, once the

engine speed varies, the compressor rate

also varied, which leads to a variation of

the refrigerant mass flow rate.

Process of heat powered adsorption in

auto motives

The performance of this adsorption ac

system is a series of adsorption and

desorption forms. After the adsorbent is

warmed up from the adsorber, the

refrigerant vapor is desorbed and

consolidated in the condenser, and the

dense fluid is moved into the evaporator.

Refrigerant vapour is again adsorbed from

the adsorbent at the adsorber from the cool

down procedure. Three chilling fans

positioned at their places assist the

process. The schematic chart of the model

amid execution is given in Figure.

In this model, the adsorber was developed

to intensify the mass and heat transport of

the adsorbent bed and optimize the number

of carbon to be packaged. The adsorber

desired a height of 10 cm, the width of 20

cm and a total length of 40 cm. The

refrigerant liquid soared through the

channels of these tubes. The total of 1.6 kg

of oil palm shell resulting Activated

carbon has been packaged between these

tubes fins. The particle size of the

triggered carbon has been less than 3.0

mm, together with outward area of 1000--

1100 m2 /g, total opening volume of 0.5--

0.6 cm3 /gram, density of 0.431 g/cm3 and

potassium amount of 1180. The warmth of

adsorption of the carbon has been 1800

kJ/kg. Air tubing with fins of heat

exchangers made of aluminum was

utilized as the evaporator and condenser.

Figure Adsorption cycle (strong lines

with bolts represent stream

Management also, the dashed lines

demonstrate the valves in the line Are

All Shut and no fluid Leaks from the

segments between the protect and the

glow exchanger)

The schematic of this adsorption structure

Suggested for vehicles is showed up in

Figure. At the point exactly when

Adsorber 1 is related with the Evaporator

and Adsorber two is related with the

condenser. The fluid from warmth sink

cools adsorber 1 and furthermore adsorbs

the refrigerant in the evaporator, giving

cooling to your vehicle or truck. All the

while Adsorber 2 is warmed by the fluid in

the shine source near to the refrigerant is

desorbed In the sorbent and after that

streams towards the evaporator through the

enhancement contraption.

4.0 RESULTS

Air conditioners in automotive

application

After developing the system models,

simulations were done using the MBVT

drive cycle for 3 different ambient

temperatures and 2 different air mass



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flows over the evaporator at each ambient

temperature. The details of the boundary

conditions are as shown below in Table.

Table Details of the comparison study

for each temperature and air mass flow

rate

MBV

T

T_ambie

nt = 22°C

T_ambie

nt = 29°C

T_ambie

nt = 35°C

[kg/min] [kg/min] [kg/min]

1,5 2 2 3 4 6

Ambient Temperature 22°C

The simulations at 22°C ambient

temperature and 55% relative humidity

were done with an air mass stream of 1,5

kg/min over the evaporator. At 29°C

surrounding (40% dampness) with a mass

stream of 2 kg/min and at 35°C (40%

humidity) with 4 kg/min. The following

simulation results are showing data of the

mechanical and electrical system in one

graph for each evaluation criterion.

The relevant criteria for this paper are: -

Pressure (suction and discharge) [bar] –

Evaporator air outlet temperature [°C] –

Refrigerant Mass flow [kg/h] – Cooling

capacity [Kw] – Coefficient of

performance (standardized) [-] In Figure ,

we can see that the suction and discharge

pressure reach their aimed ratios for both

the systems. For the electrical system both

suction & discharge pressures run more

stable, especially for the suction pressure.

This fluctuating pressure from the

mechanical system can result for example

in pulsation which negatively affect the

acoustics of such a framework.

Graph Suction and discharge pressure

of both system as a function of time

There are two main aspect visualized in

Figure. The first one is that the mass flow

for mechanical system experiences large

variations. This is caused by the fact that

the compressor is being driven via the belt

drive of the ICE. Also in the simulation

model, the compressor speed was reduced

to a minimum of 10 rpm at stop phases. A

complete stand still of the mechanical

compressor was not achievable with this

Dymola model. This leads us to the second

main aspect of Figure. Because of the

lessening of compressor speed bringing

about a decrease of mass stream, the air

outlet temperature of the evaporator

couldn’t be kept constant. For longer

periods, for example during long phases of

traffic signal, it is observed that the

temperature increases dramatically.



ISSN NO:2236-6124

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Graph Evaporator air outlet

temperature and mass flow as a

function of time

This will result in a massive discomfort in

the passenger cabin as compared to the

electrical system. The electrical scroll

compressor was operated during all stop

phases in the drive cycle that results in

maintaining the thermal comfort of the

passengers. For the electrical system in

general it is evident that it runs more stable

compared to the system with the

mechanical compressor at 22°C ambient

temperature. This hypothesis is affirmed in

Figure. The massive variation of the

cooling capacity of the mechanical system

is again linked to the stop phases. During

the stop phase it will decrease because of

the reduced compressor speed.

Graph Cooling limit and COPs as an

element of time

Also, the temperature of the evaporator

increment, as the ambient air at 22°C is

blown over it. Once the system starts

again, the system tries to reach the

evaporator air set point temperature of

3°C. Also the variation in COP of the

mechanical arrangement can be explained

with the stop phases. There it is important

to know that mechanical compressors in

automotive application have a variable

displacement which is controlled via

parameters of the refrigeration loop. So

once the car starts after a stop phase the

loop tries to reach the evaporator air set

temperature. The speed of the compressor

is fixed to the given profile so the only

chance to increase the capacity is to

upsurge the compressor displacement.

This is also shown in Figure with the

graph of the mass flow. There it is

noticeable how the mass flow is changing

due to the changes in the displacement.

Because of the design of the variable

displacement compressor it is found to be

operating in a more efficient mode at

lower speed and full displacement. In

Figure the COP is standardized because at

stop phases when the mechanical

compressor is shut of we still gain the

cooling capacity which is stored in the



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Page No:1166

refrigerant loop. But meanwhile you lose

thermal comfort in the vehicle cabin so it

is needed to take this also into

consideration in calculation of the COP.

So the factor ε is introduced for calculating

COPs. Its graph is plotted for the air outlet

temperature over the evaporator in Figure.

HEAT TRANSFER RATE

Convection

Figure Mass Run Velocity of

CONVECTION AT 1.0% of FLUID-

SILVER

Temperature

Figure Mass Run Velocity of (a)

TEMPERATURE AT 1.0% of FLUID-

SILVER

Temperature

Figure Mass Run Velocity of (b)

TEMPERATURE AT 1.0% of FLUID-

SILVER

Heat flux

Figure HEAT FLUX AT 1.0% of FLUID-

SILVER

FLUID - R134A

Temperature

Figure (a) Temperature of FLUID -

R134A



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Page No:1167

Temperature

Figure (b) Temperature of FLUID -

R134A

Heat flux

Figure Heat flux of FLUID - R134A

FLUID - R407C

Temperature

Figure (a) Temperature of FLUID - R407C

Temperature

Figure (b) Temperature of FLUID -

R407C

Heat flux

Figure Heat flux of FLUID - R407C

MATERIAL –ALUMINIUM 7075

FLUID – R22

Thermal conductivity of aluminum =

59.1W/mK

Specific heat =421 J/Kg K

Density = 0.00000771Kg/mm3

Heat flux



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Figure Heat flux of FLUID - FLUID –

R22 ALUMINIUM 7075

FLUID - R134A

Heat flux


R134A ALUMINIUM 7075

FLUID - R407C

Heat flux


R407C ALUMINIUM 7075

MATERIAL –COPPER

FLUID – R22

Thermal conductivity of aluminum =

59.1W/mK

Specific heat =421 J/Kg K

Density = 0.00000771Kg/mm

Heat flux

Figure Heat flux of FLUID – R22

COPPER

FLUID - R134A

Heat flux

Figure Heat flux of FLUID – R134A

COPPER

FLUID - R407C

Heat flux



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Figure Heat flux of FLUID – R407C

COPPER

5.0 CONCLUSION

This work concentrated on the portrayal

and the convection of different nano

liquids in forced air system, anyway

further research is required for better

comprehension of nano liquids in nano

fluids.The ebb and flow result just the

greater part of the oxide nano liquids are in

compelling as warmth exchange fluids and

certain CNT nano liquids are successful if

there should be an occurrence of vehicle

airconditioner. A conventional compelling

medium hypothesis neglected to clarify the

outcomes. More research on the oxide

nano liquids may not be required but rather

there possibly some controlling parameter

which builds the warm conductivity we

didn't perceive.

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International Journal of Research ISSN NO:2236-6124ijrpublisher.com/gallery/146-january-2019.pdf · waste heat and can help reduce needed energy and thermal contamination. Many adsorption