Copyright 2003 Chan Madan All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means without written permission by C.D. Madan.

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About the Author: Chan Madan and Liquid Chillers 101 Liquid Chillers 101 is written by Chan Madan, who has over 30 years of experience in manufacturing, designing and servicing chillers for the Air Conditioning, Refrigeration and Process cooling industry. Chan Madan is a consultant to the HVAC&R Industry. His previous publications include: Refrigeration Compressors/Chillers, HVAC Handbook, McGraw Hill Publications Industry-related articles in ASHRAE Journal (American Society for Heating, Refrigeration & Air Conditioning Engineering), trade magazine. Various articles, including How Ductless Systems Came To Be, in The Air Conditioning, Refrigeration and Heating News, trade magazine Liquid Chillers 101 is a good introduction to chillers. It has detailed information that can be useful to various people who want to learn and know more about this fascinating cooling system. This publication covers Liquid Chillers with Positive Displacement Compressors such as Reciprocating, Scrolls and Rotary Screws. It does not cover Centrifugal Chillers, which use Dynamic Compressors.

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Contents

Page

What is a Liquid Chiller? 4

What Does a Liquid Chiller Do? 5

Where are Liquid Chillers Used? 5

What are Various Types of Liquid Chillers? 6

Comparison: Air Cooled, Water Cooled and Evaporative Cooled 7

Types of Compressors as Applied to Chillers 8-9

Liquid Chiller Ratings 10

Liquid Chiller Efficiencies 11

A Short Environmental Discussion USA/Europe 11

Environmentally Friendly Liquid Chillers Today 12

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What is a Liquid Chiller? A Liquid Chiller is a refrigeration system which consists of: a) Compressor(s) b) Condenser(s) c) Refrigeration specialties: Filter drier(s) Solenoid valve(s) Sight glass(es) Expansion valve(s) d) Chiller-evaporator(s) e) Control center with power, operating and safety controls to manage the operation of the system f) The complete system is factory assembled, with all components on a common skid. Its a refrigeration machine ready to operate once the proper electric power is provided, the liquid connections are piped and there is cooling load. g) For proper installation and operation of a Liquid Chiller, a certified Refrigeration Technician is necessary. A Liquid Chiller system cools water, glycol, brine, alcohol, acids, chemicals or other fluids. The most common use of a chiller system is as a water chiller for human-comfort cool cooling application. The chilled water generated by the chiller system is circulated through the cooling coil of a fan coil (or air-handling unit), as shown below. The fan coil circulates air within the conditioned space. Air from the room moves over the chilled-water cooling coil of the fan coil, gets cooled and dehumidified, and returns back to the room. In this process, the chilled water in the cooling coil picks up the heat and is returned back to the chiller system for cooling. As the cycle is repeated, the chiller system maintains the conditioned space at the comfort level.

Typical liquid chiller system

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What Does a Liquid Chiller Do? A Liquid Chiller is a refrigeration system that cools any of the following: a.) Water b.) Propylene or ethylene glycol and water mixture c.) Brines d.) Ingredient water (e.g. for bakeries) e.) Drinking water f.) Process cooling (e.g. MRI/CAT scan machines, welders, lasers) g.) Alcohol, acids h.) Chemicals, petrochemicals or other fluids (For Process Cooling applications, see below.)

Where are Liquid Chillers Used? Air Conditioning The most common usage for Liquid Chillers is for air conditioning (comfort cooling) of multi-story offices, large hotels, hospitals, schools, places of assembly, historical buildings, some homes or wherever ducted systems are unacceptable. A typical chiller system is designed for chiller water flow to produce a temperature differential of 10 F (5 C) cooling from 54 F to 44 F ( 12 C to 4 C). Process Cooling Typical Process cooling chillers are used for: Bakeries Machine Oil Cooling Breweries Milk Cooling Candy/Fruit Glazing Mushroom Growing Chemicals/Petrochemicals Pharmaceuticals Chicken/Fish Hatcheries Photo Labs Computer/Clean Rooms Plastics Electronic Cabinet Cooling Plating/Metal Finishing Environmental Test Chambers

Pulp and Paper Explosion Proof Areas Shrimp Freezing Flight Simulators Soil Freezing Foundries Solvent Recovery Fruit Juice Cooling Steel Mills Laser Cooling Textile Plants Lobster Cooling Welding Wineries

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What are the Various Types of Liquid Chillers? 1. Air Cooled Requires air cooled condenser 2. Water Cooled Requires water cooled condenser and cooling tower, or some other source of cooling condenser water 3. Evaporative Cooled Requires evaporative cooled condenser Liquid Chillers can be further described as either Packaged or Split Systems. Packaged Liquid Chiller A packaged chiller means that all the refrigerant components (compressor, condenser, refrigeration specialties, chiller/evaporator and control center) are all factory assembled and packaged into a single pre-engineered system, ready to operate once the liquid to be cooled is properly piped, electric power is wired to the unit and that there is load to cool. Field refrigerant charge may be required. Split Liquid Chiller Systems As the name implies, chillers can be split as follows: Split (A)

Compressor(s), chiller/evaporator(s), refrigeration specialties and control center are indoor and the matching air cooled condenser is outdoor. Both components are to be field piped, pressure tested, evacuated and charged with refrigerant by a qualified refrigeration technician. Split (B) Compressor(s), air cooled condenser, control center outdoors with matching chiller/ evaporator(s) and refrigeration

specialties indoor, both components are to be field piped, pressure tested, evacuated and charged with refrigerant by a qualified refrigeration technician.

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Typical water cooled chiller

Typical evaporative cooled chiller

Comparison: Air Cooled, Water Cooled and Evaporative Cooled Air Cooled Chillers

Air cooled chillers are the most commonly used due to convenience of low maintenance. However, power usage is higher, due to the condenser fan motors (in addition to the compressor motors) which are required to move the ambient air. Depending on ambient temperatures, condensing temperatures of 120 to 140 F are required.

Water Cooled Chillers Water cooled chillers require cooling tower, city water, river water or other source of water to operate. In the case of cooling towers, maintenance is absolutely required to operate the system at optimal efficiency. However, water cooled chiller do save in operating costs. Water cooled chillers operate at lower condensing temperatures, usually 105, instead of air cooled condensing which can range from 120 to 140 F. Lower condensing temperatures save energy, approximately

20-25% over air cooled chillers Lower condensing temperatures provide longer life of compressor There are no condenser fan motors, only condenser water pump and cooling tower fan Evaporative Cooled Chillers Evaporative cooled chillers are the least known, but the most efficient, especially a factory assembled system. In an evaporative cooled system, the functions of a water cooled condenser and a cooling tower is combined. The condensing temperature of this chiller system can be as low as 85 to 105 F, depending on the ambient WB temperature. These lower condensing temperatures result in: Highest efficiency, lowest operating

costs Longer equipment life

Typical large air cooled chiller, 100 400 tons

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Reciprocating

Scroll

Rotary Screw

Types of Compressors as Applied to Chillers

Positive Displacement Compressors

Dynamic Compressors

Reciprocating Centrifugal

Rotary Screws

Scrolls

Positive Displacement Compressors Positive displacement compressors operate by increasing the pressure of refrigerant vapor by reducing the volume of the compression area through work applied to the compressors mechanism. Examples:

Dynamic Compressors Dynamic compressors operate by increasing the pressure of refrigerant vapor by continuous transfer of angular momentum from a rotating member to the vapor, followed by conversion of this momentum into a pressure rise.

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Reciprocating Compressors There are three types of reciprocating compressors.

Hermetics Hermetics are with motor and compressor mounted inside a steel shell which in turn is sealed by welding.

Semi-Hermetics Also called bolted, accessible or serviceable, semi-hermetic compressors are similar to hermetics, except the compressor body is bolted instead of welded. These compressors are field repairable. Open Drive

Open drive compressors require a shaft seal in which the shaft is extended through the seal for external (motor) drive. They can also be driven by a gas or diesel engine. This compressor is an industrial workhorse. There is no chance of motor burnout, as the motor is external.

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Liquid Chiller Ratings There is a misconception in the Air Conditioning industry that one HP is equal to one TON of cooling. For a chiller application, one HP is NOT equal to one TON of coolinghere is why: Evaporator Side Air Conditioning chillers are designed to deliver 44 F to 45 F chilled water to the cooling system. To do so, the compressor needs to be rated at 9 F to 10 F below the leaving chilled water. Therefore (44 9) 35 F is the evaporator temp. Condenser Side The other side is condensing temperature. A) For an air cooled condenser @ 95 F ambient, the condensing temperature needs to be 30 F to 40 F above ambient, which becomes equal to 125 F to 135 F condensing temp. B) For a water cooled or evaporative cooled condenser, the condensing temperature is 105 F. In view of the above, a compressor for chiller applications need to be @ 35 F suction and 125 to 135 F condensing for air cooled and 35 F suction and 105 F condensing for water cooled.

Calculation of Condenser Heat Rejection (CHR) CHR = capacity (btu/hr) + 3,415 x motor kW Typically, a 40 HP delivers: 360,000 btu/hr +3,415 x 41.8 kW = 360,000 + 142,747 = 502,747 = 42 tons Therefore, 30 real tons of chilled water-cooling will require 42 tons of air cooled condenser.

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Liquid Chiller Efficiencies How efficient a chiller system works depends on how much electric power is required to deliver a certain amount of cooling capacity, expressed in btu/hr. Examples COP (Coefficient of Performance) = capacity btu/hr input power to motor (in btu/hr) EER (Energy Efficiency Ratio) = btu/hr watt Efficiencies for most chillers are expressed in EER. Typical Air Cooled chillers are in 8.5 to 9.5 EER Typical Water Cooled chillers are in 10 to 12 EER Typical Evaporative Cooled chillers are in 12 to 15 EER Higher efficiency chillers are available from Continental Chillers LLC

A Short Environmental Discussion USA/Europe In any non-political Environmental Discussion, it is almost certain that todays CFC and HCFC refrigerants will have to be replaced with tomorrows refrigerants that have: Environmentally-friendly and safe record Zero ODP (Ozone Depletion Potential) Very low TEWI (Total Equivalent Warning Impact) The USA is largest user of refrigerants in the world. We have the highly acclaimed ASHRAE (American Society of Heating, Refrigerating, Air Conditioning Engineers) in addition to the well-respected ARI (Air Conditioning and Refrigeration Institute). Both ASHRAE and ARI are legends in their own right. The HVAC&R industry all over the world follows ASHRAE/ARI, including India and China. Yet, the USA is often oblivious to the environmental concerns. Our neighbors across the Atlantic The Europeans, already have tough environmental standardsthey dont offer any CFC or HCFC products anymore. That should tell us something! Here is the good news

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Environmentally Friendly Liquid Chillers Today Today, for environmentally friendly, technically safe and non-ozone depleting equipment, contact: Continental Chillers LLC Web: www.continentalchillers.com E-mail: sales@continentalchiller.com Tel: 317-337-9813 Fax: 317-337-9816 Ranging in sizes from 3 ton to 400 tons the new equipment is very timely considering the future legislation. For your information: In year 2004 a 35% reduction cap goes into effect for R-22. Imagine the prices of

R-22 after 2004. In year 2010 production of any new machines using R-22 ends. That means no more

R-22 equipment will be available. Today Owners, Engineers, Contractors and Distributors can safely specify, order and install CONTINENTAL s new non-ozone depleting equipment without fear of future legislation and be environmentally safe and responsible. In addition to non-cfc equipment, CONTINENTAL offers multi-stage cooling equipment with true energy savings. For example, a 100 ton machine can operate at 75%, 50% or 25% with almost 75%, 50% or 25% kW consumption. In other words, the power consumption is directly proportional to the actual usage. Traditional equipment has unloaders, hot gas bypass and other means to operate at partial loads. CONTINENTAL s multi-stage cooling offers true energy savings and redundancy in todays energy conscious world. CONTINENTAL further offers a choice of compressorsscrolls, rotary screws or recips and a choice of condensersair, water or evaporative cooled.

Liquid Chillers 101 by Chan Madan