Refrigeration Cycle Experiment

Introduction

The flow of temperature is from the high regions of temperature to the low regions of temperature. The work is produced when from the domain of high energy; the energy is transferred to the domain of low energy. Similarly, the work is consumed when from the domain of low energy; the energy is transferred to the domain of high energy. For happening of the reverse, a special device is required known as Refrigerator.

The laboratory exercise of the experiment of this study has an objective of Mechanical Refrigeration Cycle or Vapour Compression Refrigeration Cycle on the diagram of Pressure-Enthalpy property pertaining to a Refrigeration Cycle. Its thermal performance is assessed with COPREF (Coefficient of Performance) (Dincer, 2003).

The mechanical refrigeration apparatus’ components are identified along with the occurrence of thermodynamic processes in these components. These processes are analyzed in expansion/ throttle valve, compressor, evaporator, and condenser. In various thermodynamic states, refrigerant’s gas and the liquid phase will be measured in terms of pressures and temperatures in constructing the refrigeration cycle. The water flow rates are measured through condenser and evaporator along with the flow rate of the refrigerant.

The procedure followed in this paper is that of normal operation (Whitman, 2008). Solkane SES36 is the refrigerant which is shown in the Solkane SES36 Pressure-Enthalpy diagram (Figure 1).

Analysis

From the testing data, the following figures can be obtained.

me = 10
Cp = 4.18
t1 = 15.3
t2 = 13.8
Putting these figures in the formulae:
Qe = 10x4.8(15.3 – 13.8)
= 48 (1.5)
= 72
Qc = mcCp (t3 – t4)
Here,
mc = 6, t3 = 20.4, t4 = 16
Therefore,
Qc = 6x4.8 (20.4 – 16)
= 28.8 (4.4) = 126.72

Although Pcomp and Pmech both have the same value of 164, they are essentially different. Pcomp is the power input of the refrigerant, where Pmech is the mechanical power input to drive the compressor being measured.

Discussion

The cycle of vapor compression has the common use of mechanical refrigeration or the refrigeration cycle and the involvement of the identical four processes as a cycle of heat engine, although in a reverse order. The reverse order starts with evaporation, which is followed by compression, and further followed by condensation, and finally throttling/expansion. The four main components’ schematic representation of the system has been in the Figure2. The states of thermodynamics that is correspondent to it have the representation in Figure 3.

The vapor compression cycle’s work input drives a compressor maintaining in the condenser a high pressure and in an evaporator a low pressure. The temperature where there will be condensation of vapor or evaporation of liquid depends on the pressure. Therefore, if there is introduction of refrigerant or the suitable liquid, the evaporation of it will take place at a low temperature in the evaporator of low pressure and will be condensing in the high pressure condenser heat at a higher temperature (Çengel and Boles, 2004). Therefore, at a low temperature, the refrigerant has taken the heat and at a higher temperature it has rejected heat. In the condenser, the high pressure liquid thus formed at a controlled rate should be returned to the evaporator via the expansion valve.

References

• Dincer, I. (2003) Refrigeration Systems and Applications, John Wiley and Sons, p. 598.
• Whitman, B. (2008) ‘Refrigeration and Air conditioning Technology’, Delmar.
• Çengel, Y. A. and Boles, M. A. (2004) Thermodynamics: An Engineering Approach, 5th edition.