Experiment 1: Refrigeration and Mechanical Heat Pump Experiment
Experiment 1: Refrigeration and Mechanical Heat Pump Experiment
In this experiment, students will learn about the principles and applications of refrigeration and mechanical heat pump systems. They will use a thermodynamic cycle simulator to model the performance of a vapor-compression refrigeration system and a mechanical heat pump system under different operating conditions. They will also measure the actual coefficient of performance (COP) of a refrigeration unit and compare it with the theoretical value.
The objectives of this experiment are:
Experiment1RefrigerationandMechanicalHeatPumpExperimentpdf
To understand the basic components and operation of a vapor-compression refrigeration system and a mechanical heat pump system.
To analyze the thermodynamic cycle of a refrigeration system and a heat pump system using a pressure-enthalpy diagram.
To calculate the theoretical COP of a refrigeration system and a heat pump system using the first law of thermodynamics.
To measure the actual COP of a refrigeration unit and compare it with the theoretical value.
The equipment used in this experiment are:
A refrigeration unit with a compressor, a condenser, an expansion valve, and an evaporator.
A thermodynamic cycle simulator software that can plot pressure-enthalpy diagrams and calculate COP values.
A digital thermometer, a pressure gauge, and a wattmeter to measure the temperature, pressure, and power input of the refrigeration unit.
The procedure of this experiment are:
Set up the refrigeration unit and connect it to the power supply.
Turn on the refrigeration unit and let it run for 10 minutes to reach steady state.
Measure and record the temperature and pressure at different points of the refrigeration cycle (compressor inlet, compressor outlet, condenser outlet, expansion valve outlet, evaporator outlet).
Measure and record the power input of the compressor using the wattmeter.
Use the thermodynamic cycle simulator software to plot the pressure-enthalpy diagram of the refrigeration cycle and calculate the theoretical COP.
Calculate the actual COP of the refrigeration unit using the measured data and compare it with the theoretical value.
Repeat steps 2 to 6 for different settings of the expansion valve (high, medium, low) and observe how they affect the performance of the refrigeration system.
Switch the mode of the refrigeration unit to heat pump mode and repeat steps 2 to 7 for different settings of the expansion valve (high, medium, low) and observe how they affect the performance of the heat pump system.
The expected results and discussion points are:
The theoretical COP of a refrigeration system is higher than that of a heat pump system for the same operating conditions.
The actual COP of a refrigeration unit is lower than the theoretical COP due to irreversibilities such as friction, heat loss, pressure drop, etc.
The COP of a refrigeration system or a heat pump system increases as the expansion valve setting decreases (higher throttling effect).
The pressure-enthalpy diagram shows that a higher expansion valve setting results in a larger area enclosed by the cycle curve, which means more work input and more heat output.
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