# Thermodynamics Lab

Topics: Heat, Thermodynamics, Heat transfer Pages: 9 (1872 words) Published: April 18, 2013
Abstract:

This report will show the acquired understanding of the refrigeration cycle by using first and second laws of thermodynamics. In order to analyze this system several assumptions where made such like an isentropic process at the compressor an isenthalpic expansion in the throttling valve. Diagrams will be provided to depict these thermodynamic processes in addition to computing the heat transferred to the system and the work input to the compressor.

Abstract .................................................................................................................................................... 2 Table List ................................................................................................................................................. 3 Introduction.............................................................................................................................................4 Descriptions…………...............................................................................................................................5 Theory………………….............................................................................................................................. 7 Calculation................................................................................................................................................8 Discussion. ............................................................................................................................................. 11 References.............................................................................................................................................. 15 Appendix................................................................................................................................................. 16

Objectives:
The Refrigeration lab was conducted to gain a better understanding of the refrigeration cycle, Carnot cycle and to compare the ideal cycle. Also, determent the heat transfers by using the mass and energy balance.

Introduction:
The term “refrigeration” may be defined as the process of removing heat from a substance under controlled conditions. It also includes the process of reducing and maintaining the temperature of a body below the general temperature of its surroundings. In other words, the refrigeration means a continued extraction of heat from a body whose temperature is already below temperature of its surroundings. In this lab 1,1,1,2-Tetrafluoroethane (R-134a) was used as refrigerant. Since energy cannot be destroyed according to first law of thermodynamics. In a refrigerator, heat is virtually pumped from a lower temperature to a higher temperature. According to Clausius Statement of Second Law of Thermodynamics states that heat will not pass cold to hotter region without the aid of an external agency. Thus, process can only be performed with the aid of some external work. It is thus obvious that supply of power is regularly required to drive a refrigerator. Theoretically, a refrigerator is a reversed heat engine or a heat pump which pumps heat from a cold body and delivers it to a hot body. The substance, which works in a pump to extract heat from a cold body and to deliver it to a hot body, is known as refrigerant.

Description of Refrigeration cycle description:

Most commonly used refrigeration/heat pump cycle and involves the same four processes as a heat engine cycle but in the reverse order (i.e. evaporation – compression – condensation – expansion/throttling). Figure 1 gives a schematic representation of the four essential mechanical components in this cycle.

Heat out

3 2

Condenser

Throttle Work in
Valve
Evaporator Compressor

4 1

Heat in

Figure 1:...