Mini Ice Plant Report

MINI ICE PLANT EFFICIENCY PERFORMANCE AND PROCESSES

The term ice plant is used in this note to mean a complete installation for the production and storage of ice, including the icemaker itself, that is the unit that converts water into ice together with the associated refrigeration machinery, machinery, harvesting and storage equipment, and the  building. It is used for producing refrigeration effect to freeze potable water in standard can spliced in rectangular tank which is filled by brine. A good definition of refrigeration is the removal of heat energy so that a space or material is colder than its surroundings. An ice plant based on same  principle as a simple simple refrigeration system. An ice plant contains contains various  parts such as compressor, compressor, condenser condenser,, receiver, receiver, expansion valve, and evaporator and refrigeration accumulator. accumulator. A refrigeration is always been a great deal for human being and play a vital role in preserving food , chemical, medicine, fisheries and providing appropriate temperature in working Entity of any industry. industry. Refrigeration in the coming years  becomes very essential essential deal for drastic development of the industrial sector.

INTRODUCTION

The term ice plant is used in this note to mean a complete installation for the production and storage of ice, including the icemaker itself, that is the unit that converts water into ice together with the associated refrigeration machinery, machinery, harvesting and storage equipment, and the  building. It is used for producing refrigeration effect to freeze potable water in standard can spliced in rectangular tank which is filled by brine. A good definition of refrigeration is the removal of heat energy so that a space or material is colder than its surroundings. An ice plant based on same  principle as a simple simple refrigeration system. An ice plant contains contains various  parts such as compressor, compressor, condenser condenser,, receiver, receiver, expansion valve, and evaporator and refrigeration accumulator. accumulator. A refrigeration is always been a great deal for human being and play a vital role in preserving food , chemical, medicine, fisheries and providing appropriate temperature in working Entity of any industry. industry. Refrigeration in the coming years  becomes very essential essential deal for drastic development of the industrial sector.

INTRODUCTION

1. Meat and Poultry Storage

2. Fish Storage 3. Milk Products such as Ice Cream 4. Drinks or beverages 5. “Ice Water” Water” or water stored in a piece of plastic which is sold at sari-sari stores in the philippines

 APPLICATION OF A MINI ICE  APPLICATION PLANT

Ice plants are usually classified by the type of ice they produce; hence there are block ice plants, flake ice plants, tube, slice or  plate ice plants and so on. Ice plants may be further subdivided into those that make dry or wet ice. Dry ice here means ice at a temperature low enough to prevent the particles becoming moist; the term does not refer in this note to solid carbon dioxide. In general,, dry subcooled general subcooled ice is made in plants plants that mechanical mechanically ly remove the ice from the cooling surface; most flake ice plants are of this type. When the cooling surface of an icemaker ic emaker is warmed  by a defrost mechanism to release the ice, the surface of the ice is wet and, unless unless the ice is then subcooled subcooled below 0°C, 0°C, remains remains wet in storage; tube ice and plate ice plants are of this type.

CLASSIFICATION

 Block ice Tapered rectangular metal cans filled with water are immersed in a tank containing refrigerated sodium chloride brine. The dimensions of the can and the temperature of the brine are usually selected to give a 24 hour production time, and batches of cans are emptied and refilled in sequence during that period. Ice block weight can range from 12 to 150 kg depending on requirements; 150 kg is regarded as the largest size of  block one man can conveniently handle. A block ice plant requires continuous attention and is labour intensive. The icemaker and the store require a good deal of floor space and impose heavy loads on the  building structure. For these reasons block ice plants are going out of use, and more modern automatic plants are replacing them.

TYPES OF ICEMAKER

 Rapid block ice It is possible to reduce the freezing time for blocks considerably, and thus reduce the space required for the icemaker. This is done by reducing the thickness of ice to be frozen; in one type of rapid icemaker this is achieved  by passing refrigerant through tubes around which the ice forms and fuses into a block. The blocks can be released by defrosting and harvested automatically, thus markedly reducing the labour requirement, but the storage space required is slightly larger than for the same weight of conventional block ice because the blocks have hollow centres after the tubes are removed.

TYPES OF ICEMAKER

 Flake ice A sheet of ice 2-3 mm thick is formed by spraying water on the surface of a refrigerated drum, and scraping it off to form dry subcooled flakes, usually 100-1000 mm2 in area. In some models the drum rotates against a stationary scraper on its outer surface; in others the scraper rotates and removes ice from the inner wall of a double walled stationary drum. In some models the drum is horizontal, but more usually it is mounted vertically. No water is sprayed on that part of the drum immediately before the scraper, so that the ice becomes dry and subcooled prior to removal. Refrigerant temperature, drum or scraper speed, and degree of subcooling are all variable within designed limits so that the capacity of the icemaker and the thickness of the ice can be altered. Typical refrigerant temperature in a flake ice machine is - 20 to - 25°C, lower than in most other types of icemaker, to give rapid cooling and thus make the machine compact. The low operating temperature requires more power,  but this is to some extent compensated for by the absence of a need to defrost.

TYPES OF ICEMAKER

Tube ice Water is frozen on the inner surface of vertical refrigerated tubes to form hollow cylinders of ice about 50 mm in diameter and with walls 10-12 mm thick. The ice cylinders are released  by defrosting the tubes automatically, and are chopped into pieces about 50 mm long  by a rotating cutter as they slide out. The cylindrical pieces can  be subcooled by storing them at - 5°C, but they may require further crushing before being suitable for some applications in the fish industry.

TYPES OF ICEMAKER

 Plate ice Water is frozen on one face of a vertical refrigerated plate, and the sheet of ice is released by running warm water on the other face of the plate. The size of ice  particle is variable, but the optimum thickness is 10-12 mm. The plates are usually mounted in banks, often above the refrigeration machinery, to form a self contained unit. Water for defrosting has to be heated if its temperature is below 23°C. Like most other icemakers the plate ice machine will operate unattended on an automatic timing cycle. Other icemakers Machines are available that make ice by methods other than those described here,  but the size of unit is usually small, producing at the most only a few hundred kilograms of ice a day; these are suitable for retail and catering services, but are unlikely to be of interest to those providing icemaking services to the catching and  processing sectors of the fish industry.

TYPES OF ICEMAKER

Manufacturers usually quote a wide range of daily output for specific icemaker units, because their capacity can be affected by a number of factors, but this flexibility usually exists only at the  planning stage; once the icemaker has been matched to suitable refrigeration machinery under given operating conditions, there is little scope for changing the capacity of the installed unit. Changes in demand are best catered for by reducing running time or by installing multiple units and operating only as many as arc needed. Since the capacity of both the icemaker and the refrigeration machinery is lower in warmer weather, the size of the plant should be selected for warm weather operation, when demand for ice is also likely to be greatest.

CAPACITIES OF ICEPLANTS

COMPONENTS AND PROCESS

Compressor A refrigerating compressor, as the name indicates, is a machine used to compress the vapour refrigerant from the evaporator and to raise its pressure so that the corresponding saturation is higher than that of the cooling medium. It also continually circulates the refrigerant through the refrigerating system. Since the compression of refrigerant requires some work to be done on it, therefore a compressor must be driven by some prime mover.

COMPONENTS OF A MINI ICE PLANT

Condenser The condenser is an important device used in the high pressure side of a refrigeration system. Its function is to remove heat of hot vapour refrigerant discharge from the compressor. The hot vapour consists of the heat absorbed by the evaporator and the heat of compression added by the mechanical energy of compressor motor. The heat from the hot vapour  refrigerant in a condenser is removed first by transferring it to the walls of the condensers tubes and then from the tubes to the condensing or cooling medium. The high temperature, high pressure ammonia vapour is condensed in a condenser which may be of shell and tube type or evaporative type. The selection of the condenser depends of the capacity of the refrigerating system, the type of refrigerant used and the type of cooling medium available. Generally the condensers used are water cooled condensers (the water cooled condensers are further divided into waste water and re-circulated water system type) and evaporating condensers.

COMPONENTS OF A MINI ICE PLANT

Receiver A liquid receiver will be required if it is necessary to temporarily store refrigerant charge within the system, or to accommodate the excess refrigerant arising from changing operating conditions. The total refrigerant charge required in a circuit will vary with different operating loads and ambient, and must be sufficient at all times so that only liquid enters the expansion valve. A receiver requires a minimum operating charge which adds to overall charge and cost, and also increases system complexity. Hence receivers are avoided on many smaller systems. The total refrigerant charge required in a circuit will vary with different operating loads and ambient, and must be sufficient at all times so that only liquid enters the expansion valve. This implies that, at times, the circuit would have too much charge, which would back up in the condenser and reduce its efficiency. A drain tank is required directly after the condenser which can hold this reserve of liquid, and is termed the receiver.

COMPONENTS OF A MINI ICE PLANT

EXPANSION VALVE The expansion device (also known as metric device or throttling device) is an important device that divides the high pressure side and the low pressure side of a refrigerating system. It is connected the receiver (containing liquid vapour at high  pressure) and the evaporator (containing liquid refrigerant at low pressure). The expansion device performs the following functions like to reduce the high pressure liquid refrigerant to low pressure liquid refrigerant before being fed to the evaporator and to maintain the desire pressure difference between the high and low pressure side of the system, so that the liquid refrigerant vaporizes at the designed pressure in the evaporator. There are many types of expansion devices used viz. capillary tubes, automatic or constant pressure expansion valve, low side float valve, high side float valve and thermostatic expansion valve in an ice plant industry depending upon its capacity The capillary tube is used as an expansion device used in small capacity hermetic sealed refrigeration units such as domestic refrigeration, water cooler, room air conditioner and freezers. It is a cooper tube of small diameter and of varying length depending upon the application. Figure

COMPONENTS OF A MINI ICE PLANT

Evaporator The evaporator is an important device used in the low  pressure side of the refrigeration system. The liquid refrigerant from the expansion valve enters into the evaporator where its boil and change into vapour. The function of the evaporator is to absorb heat from the surrounding location or medium which is to be cooled, by mean of a refrigerant. The temperature of the boiling refrigerant in the evaporator must always be less than that of the surrounding medium so that heat flows to the refrigerant

COMPONENTS OF A MINI ICE PLANT

Space Modern icemakers arc compact in comparison with block ice equipment, but it is not always possible to compare directly the space occupied by different types; for example they may not be available in the same unit sizes. However some guidance on the space requirements for icemakerswith a nominal capacity of 50 tonnes a day is given in Table 1; the figures are for icemakers only, and the space for refrigeration machinery, handling and storage will usually amount to far more than for the ice-maker. Table 1 Space required for an icemaker producing 50 t/day 

type of ice

floor area m2

height m

block

190

5·0

rapid block

30

3·5

tube

3·3

6·6

flake

2·7

3·7

ICE PLANT REQUIREMENTS

Power   Average power and peak power requirements may be different, and both have to be considered at the planning stage. The average power relates to the energy consumed in making a tonne of ice, and this is important in calculating operating cost. Peak power is important to the designer since it will determine what electrical supply is required, and may also affec t operating cost if a peak demand factor is applicable. The energy required to make a tonne of ice is not constant. It varies widely depending on a number of factors, the most important of which are type of icemaker  operating temperature make-up water temperature cooling water temperature air temperature size of plant utilization of plant method of refrigeration Energy consumption figures quoted by manufacturers for unspecified operating conditions should be used only as a general guide. The values given in table 2 show how energy requirements can increase c onsiderably in warm climates. Table 2 Energy required to manufacture ice kWh/tonne

type of ice

temperate area

tropical area

flake

50-60

70-85

tube

40-50

55-70

block

40-50

55-70

ICE PLANT REQUIRMENTS

Water  In addition to water for making ice, water may be required for cooling, as in a refrigeration plant condenser, or for heating, as in a warm water defrosting system. The amount of water required for making ice is roughly equal to the amount of ice  being produced plus some allowance for wastage and for prevention of build up of solids in the water circulating system. Fresh water for making ice for use with fish must satisfy the requirements for drinking water. In addition, the chemical composition of water for making ice must meet the equipment manufacturers' requirements; hard water containing excessive amounts of solids may foul the icemaker and may also yield a soft wet ice. On the other hand pure water may cause problems, particularly in flake ice plants, because the ice sticks hard to the drum; the remedy is to fit a dosing device that puts 200-500 g salt into each tonne of water to improve release of the ice without making the ice detectably salty when used on fish. Water for defrosting plate icemakers has to be of the same high quality as water for making ice. About 2 tonnes of water is required for each tonne of ice if the water is run to waste, but consumption can be reduced to almost nothing by making a closed circuit and reheating the water between defrosts.

ICE PLANT REQUIREMENTS

Most modern icemakers are designed to work unattended 24 hours a day with only routine inspection and maintenance. The system is therefore designed for reliability, with safeguards against failure or malfunction. Most manufacturers recommend the refrigeration system best suited to their icemakers, but where local installation engineers propose a system, the purchaser should ensure that the contractor is aware of the need for continuous automatic running and for rapid repair after breakdown. The refrigeration system for an icemaker should be independent of any other refrigeration requirement; it should not be shared for example with a freezer or a cold store. The only exception to this rule is when a complex system is installed and a competent engineer is in fulltime attendance. Manufacturers often recommend a separate system for each icemaking unit, so that in a multiple unit installation there is considerable flexibility, and a reasonable guarantee that at least some of the units are always in production. Choice of refrigeration machinery and of refrigerant is a  job for the refrigeration expert, and the advice of the ice plant manufacturer or competent consultant should be sought before making any decision.

THE REFRIGERATION SYSTEM

Storage of ice Manufacture of ice can seldom be m atched to meet immediate demand; therefore storage is necessary to cater for peak demand and to allow the icemaker to be operated continuously. Storage also acts as a buffer against interruption of production due to breakdown or routine maintenance. The size of store required will depend on the pattern of operation, but it is never advisable to store less than 2 days' production, and in most installations it is useful to be able to store 4-5 times the daily production. Stowage rates vary with the k ind of ice being made, and Table 3 gives the st orage space required for the principal types. Table 3 Storage space for ice The type of ice storage m ay range from a simple insulated bin to a large refrigerated silo or bin with automatic loading, unloading and weighing of ice

type of ice

space m³/tonne

flake

2·2-2·3

plate

1·7-1·8

tube

1·6-2·0

crushed block

1·4-1·5

STORAGE OF ICE

Silo Storage Silos are generally used only for freeflowing subcooled ice, such as flake ice, and an independent refrigeration system for the silo is essential to keep the ice sub-cooled in storage. It is usual to provide an air cooler to refrigerate the jacket space between the inner lining of the silo and the outer insulated structure; typically the air cooler is located next to the icemaker on top of the silo, and cold air either falls by gravity into the jacket or is circulated by fan. Ice is removed from the bottom of the silo, gravity flow being assisted by an agitator, usually a rotating chain; this means the oldest ice is always used first. Ice adhering to the silo wall needs to be freed periodically; otherwise this wall of ice becomes permanent, and only the central core of ice in the silo remains freeflowing. Silo storage is expensive for small amounts of ice; units have been made to hold as little as 10 tonnes, but silos are best suited for storing 40100 t.

STORAGE OF ICE

 Bin storage Bins can be used to store any kind of fragmented ice, and may be of any size from a simple box to hold 1/2 tonne to an installation holding 1000 t or more. Refrigeration of the bin is not always essential but, whatever the size, adequate insulation is n ecessary to reduce meltage; 100-150 mm of cork, or an equivalent thickness in many other suitable insulating materials, should be used. A simple bin system is suitable for factories making ice for their own use. The icemaker can be mounted above the bin, so that ice flows by gravity to a take off point at the bottom of the bin; thus the oldest ice is used first. Where ice has to be distributed to customers, bins with a capacity of up to 50 tonnes can be made with a sloping floor and so mounted that rapid discharge direct to lorry or conveyor is possible. Some means of access to the bin is advisable in order to be able to dislodge any compacted ice.  Block ice storage Block ice can be crushed and stored in the same way as other fragmented ice, but it is more usual to store the blocks and crush them as required before delivery of the ice. Because of their weight and shape it is difficult to store blocks other than in a single layer; thus a considerable floor area is required. However there is usually some extra storage available in the icemaker itself, since all of the ice cans are normally kept full.

STORAGE OF ICE

Icemakers located directly above the store feed the ice by gravity. Where an ice-maker produces wet ice, it is advisable to drain off excess water before storing it; this is normally done on a conveyor between icemaker and store. Large bins require some means of distributing ice evenly throughout the storage space; silos and small bins do not require such an arrangement. Pneumatic systems have been used for moving ice, but the method is unsuitable for ice that is to be stored again. The energy used in moving the ice is dissipated as heat which can cause some meltage, and more heat is transferred to the ice from the blown air, unless the air is  precooled. Ice can be weighed automatically on a conveyor belt to within ± 2 per cent. Elsewhere ice is usually measured by volume, the contents of a standard container having been weighed to determine the density. Weight of crushed block ice supplied is checked by counting the number of blocks delivered to the crusher.

HANDLING, CONVEYING AND WEIGHING

Usually the objectives od a performance test of a mini ice  plant are as follows: •

To carry out actual ice formation test

•

To calculate the actual C.O.P of the system

•

To calculate the theoretical C.O.P

PERFORMANCE TEST OF A MINI ICE PLANT

Refrigeration is the process of removing heat from where it is not wanted. Heat is removed from food to preserve its quantity and flavour. It is removed from room air to establish human comfort. Therefore, as heat is removed, a space or material becomes colder. The more heat is removed, the colder it becomes. The Ice Plant Test Rig designed by us works on simple vapour  compression refrigeration cycle and uses R134a or R 404 A as a refrigerant. The system is designed such that students can observe and study ice formation process without any confusion. It is also useful to understand working of vapour compression system, due to its sophisticated yet simple  performance and controls. The first procedure of ice making is Pull down test. This process would enable to lessen the time of actual ice formation. The pull down test is done with the cooling of the secondary refrigerant in the tank, brine, lowering its temperature to at least -4 to -5 degrees Celsius. There are still different factors considered in the Pull down test and this  procedure has its independent cooling load calculation.

PULL DOWN TEST

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• • •

Put the machine in the proper position where its level is horizontal and it is well ventilated. The machine must have at least 1.5 meters clearances from all sides. Give 230 volts, 50Hz, and 1 phase supply to the unit. Fill tank with brine solution of propylene glycol with approx. 20% and mix it thoroughly with water in tank (supplied). Start the compressor by putting the switch ON. Check suction and discharge pressures, check the energy-meter reading. Allow the unit to run until the temperature of the brine reaches -4 to -5 C. Record all data time for every change in value as appropriate and the corresponding pressure reading. Using the available table for R134a, take the corresponding enthalpy for every increase in pressure. Interpolate as possible. Calculate the coefficient of performance (COP). Make a graph between the time and COP. Compute the data needed by the tables. 

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•

• • •

PROCEDURES

Mini Ice Plant and its accessories - A working scale model for the study on analysis and fabrication of an Ice Plant. Beaker - A simple container for stirring, mixing and heating liquids commonly used in many laboratories. Beakers are generally cylindrical in shape, with a flat bottom. Most also have a small spout (or "beak") to aid pouring as shown in the picture. Beakers are available in a wide range of sizes, from one millilitre up to several litres. Digital Thermometer  - is a device that measures temperature or temperature gradient using a variety of different principles. A thermometer has two important elements: the temperature sensor in which some physical change occurs with temperature, plus some means of converting this physical change into a numerical value. KW-Hour meter - is the electric meter that measures the amount of electrical energy in kWh that was consumed in the house. The kWh meter has a counter display that counts units of kilowatt-hour (kWh). The energy consumption is calculated by calculating the difference of the counter's reading in the specified period. Low - side pressure gauge - A gauge which measures the pressure in the cooling side of the ice plant. High - side pressure gauge - The gauge which measure the compressing side of the ice plant. •

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 APPARATUS

Lap Time

Suction Pressure (psi)

Discharge pressure (psi)

After compression

20 30 40 45 45 45 45 45 45 45 43 48 48 48 43 40 39 39 36 32 31 30

140 160 168 173 173 173 173 173 173 173 160 160 160 160 160 160 160 155 152 150 147 140

73 76 80 82 83 85 85 85 84 84 84 84 84 84 84 84 81 81 79 78 77 76

Refrigerant Temperature ( C) After Condensation After Expansion

After Evaporation

KWHR 

(min)

0:00 0:00 15:00 17:00 20:00 22:00 24:00 25:00 27:00 29:00 30:00 31:00 32:00 33:00 34:00 35:00 38:00 40:00 43:00 47:00 50:00 53:00

43 41 41 43 42 42 42 42 41 41 41 41 42 41 41 41 41 40 40 39 38 38

11 11 11 13 12 13 12 12 12 11 11 11 11 10 10 10 8 7 7 5 4 3

16 26 26 18 17 15 13 12 11 10 9 8 5 4 4 3 4 3 3 -1 -2 3

6.8 6.8 6.8 6.8 6.9 6.9 6.9 6.9 6.9 6.9 6.9 6.9 6.9 6.9 7 7 7 7 7 7.1 7.1 71

Time

Suction Pressure (Psi)

Discharge Pressure (Psi)

0 0 15 17 20 22 24 25 27 29 30 31 32 33 34 35 38 40 43 47 50 53 57

20 30 40 45 45 45 45 45 45 45 43 48 48 48 43 40 39 39 36 32 31 30 29

140 160 168 173 173 173 173 173 173 173 160 160 160 160 160 160 160 155 152 150 147 140 138

200 180 160 140 120 100

Suction Pressure (Psi) Discharge Prssure (Psi)

80 60 40 20 0 0

0 15 17 20 22 24 25 27 29 30 31 32 33 34 35 38 40 43 47 50 53 57

This graph shows the relationship of the time to the suction pressure and the discharge pressure. This shows that the times go further, the

After compression 73 76 80 82 83 85 85 85 84 84 84

After Condensation 43 41 41 43 42 42 42 42 41 41 41

84 84 84 84 84 81 81 79 78

41 42 41 41 41 41 40 40 39

44

43

42

41

40

39

38

37

36

35

34 73

76

80

82

83

85

85

85

84

84

84

84

84

84

84

84

81

The graph shows the relationship of the temperature after compression to the temperature after condensation. This

81

79

78

77

76

75

Temperature after Expansion

Temperature after Evaporation

11 11 11 13 12 13 12 12 12 11 11 11 11 10 10 10 8 7 7 5 4 3

16 26 26 18 17 15 13 12 11 10 9 8 5 4 4 3 4 3 3 -1 -2 -3

30

25

20

15

10

5

0 11

-5

-10

11

11

13

12

13

12

12

12

11

11

11

11

10

10

10

8

7

7

5

4

3

2

Brine is a solution of salt usually sodium chloride in water . In different contexts, brine may refer to salt solutions ranging from about 3.5%. A typical concentration of seawater, or the lower end of solutions used for  brining foods up to about 26%. A typical saturated solution is depending on temperature.

BRINE

POLYURETHANE

FILM COEFFICIENT

Thickness (Side)

0.0986 m

Thickness (Bottom)

0.0508 m

Thermal Conductivity

8.29 W/mK 

Inside air film

22.7 W/mK 

Outside air film

8.29 W/mK 

Brine film

600 W/mk 

BRINE Length (cm) 55.3 35.4

outside inside Level

STAINLESS STEEL Thickness

0.2 mm

Thermal

16 W/mK 

Conductivity

Width (cm) 42.6 21.2

Depth(cm) 36.2 31.1 24 cm

GALVANIZED STEEL Thickness

0.2 mm

Thermal

18 W/mK 

Conductivity

MATERIAL PROPERTIES

Considering the steady-state cyclic operation of the system shown in Figures 1 and 2, refrigerant vapour enters the compressor at state 4 and saturated liquid exits the condenser at state 1.The refrigerant then flows through the expansion valve to the evaporator. Referring to Figure 1, using the first law of thermodynamics and the fact that change in internal energy is zero for a cyclic process, we get Qcond + Qloss, cond – (Qevap + Qloss, evap) – (W – Qloss, W) = 0 (1) where Qcond is the rate of heat rejection in condenser (kW), Qloss, cond is the rate of heat leak from the hot refrigerant (kW), Qevap is the rate of heat absorbed by the evaporator (kW), Qloss, evap is the rate of heat leak from the ambient to the cold refrigerant (kW), W is the rate of electrical power input to compressor (kW) and Qloss, W is the rate of heat leak from the compressor shell to ambient (kW). Heat transfer to and from the cycle occurs by convection to flowing fluid streams with finite mass flow rates and specific heats. Therefore, the heat-transfer rate to the cycle in the evaporator becomes Qevap = (εC) evap (Tin, evap – Tevap) = mref (h2 - h3) (2)

where ε is the effectiveness of heat exchanger, C is capacitance rate for the external fluids (kW/K), Tin, evap is the evaporator coolant inlet temperature (K), Tevap is refrigerant temperature in the evaporator (K), mref is the mass flow rate of refrigerant (kg/s) and h is specific enthalpy of refrigerant at state point (kJ/kg).Similarly, the heat-transfer rate between the refrigeration cycle and the sink in the condenser is Qcond = (εC) cond (Tcond – Tin, cond) = mref (h6 - h1) (3) where, Tcond is the refrigerant temperature in the condenser (K) and Tin,cond is the condenser coolant inlet temperature (K).The  power required by the compressor, described in terms of an isentropic efficiency, is given by W = mref (h5 - h4) (4) We assume that the heat leaking into the suction line is Qloss, evap = mref (h4 - h3) (5)