Category: Introduction to Refrigeration

The power consumption of a refrigerating machine is determined in terms of kW. However the power consumption of the driving motor is sometimes rated in horsepower (H.P). we have where Wref is in kW and HP is in metric units, where Q1 = refrigerating capacity in kW Since 1 TR = 3.5167 kW, therefore Example 18.4 The ambient air temperature during…

Heat Engine: In a heat engine, as shown in Fig. 18.4(a), the heat supplied to the engine is converted into useful work. If Q2 is the heat supplied to the engine and Q1 is the heat rejected from the engine, then the net work done by the engine is given by,   We =Q2 −Q1 Efficiency of heat engine, Refrigerator: A refrigerator is an…

The reversed Carnot cycle is shown in Fig. 18.3 on p-v and T-s. diagrams. The sequence of operations is given below: The Carnot cycle is practically not feasible since isothermal energy rejection requires extremely slow motion followed by isentropic process during which the piston should move at extremely faster rate, which is mechanically not obtainable. The COP of reversed Carnot…

During evaporation, the liquid-vapour refrigerant absorbs its latent heat of vapourisation from the medium (air, water, brine) which is to be cooled. This heat which is absorbed by the refrigerant is called the refrigeration effect. In other words, the refrigeration effect is the amount of cooling produced.   Refrigeration effect = Enthalpy of vapour refrigerant…

The capacity of a refrigeration unit is given in tons of refrigeration. A ton of refrigeration is defined as the quantity of heat to be removed in order to form one ton of ice in 24 hours when the initial temperature of water is 0°C. 1 ton of refrigeration, TR = 211 kJ/min or 3.5167 kW. Taking…

The methods of refrigeration are: 1 Vapour Compression Refrigeration System The schematic diagram of simple vapour compression refrigeration system is shown in Fig. 18.1. It consists of the following five essential parts: Note: In any compression refrigeration system, there are two different pressure conditions. One is called the high pressure side and other is known as low pressure side. The high…

A refrigeration system is a device to produce the refrigeration effect. Some of the popular refrigeration systems are:

The process of producing cold by artificial means may be called refrigeration. The term ‘refrigeration’ may be defined as the artificial withdrawal of heat, producing in a substance or within a space, a temperature lower than that which would exist under the natural influence of surroundings. In other words, the refrigeration means a continued extraction…