POLITEKNIK KOTA KINABALUSABAH

MECHANICAL ENGINEERING DEPARTMENT

CODE : J2006

COURSE : THERMODYAMICS 1

TOPIC : REFRIGERATION LABORATORY UNIT

EXPERIMENT 1: VAPOR-COMPRESSION REFRIGERATOR

1.0 Objectives

i. To understand the basic working principles of a vapor-compression refrigerator and its components.

ii. To sketch the Ts and P-h diagrams for a vapor-compression refrigerator.

2.0 Theory

3.0 Equipments / Tools

4.0 Safety and Health

i. Always make sure that water supply is connects before the experiment start.

ii. Set the spring scale to zero before experiment start.

iii. Do not try to change the setting of the meter.

iv. Ensure that the electrical console is dry at all times to prevent electrical shock.

5.0 Procedures

5.1 Setup Procedures

i. Connect the hose to connector of the machine, one to water supply and the other one to drain. Fully open the flow meter control valve, after that slowly open the water supply as well. Do not let the water flow rate over the maximum level (50g/s).

ii. Plug the 3 pin plug to the 240 AC main power supply. Turn ON the power supply.

iii. Switch ON the main switch at the side of the machine panel.

iv. Check all the display meters. Ensure that they are function by turning the selector switch to check each temperature point reading.

v. Switch ON the heater and compressor.

vi. The indicator of refrigerator flow meter will float up and shows the refrigerant flow rate as the compressor being turn ON. Meanwhile the spring scale also will show the loading on the motor.

vii. Disconnect water supply hose once the experiment finish.

5.2 Experiment Procedures

i. Switch ON the main switch located at the side of control panel.

ii. Record down all the initial reading display on the meter and gauge by turning the selector

a) Temperature

b) Pressure

c) Water – Mass flow rate

d) Refrigerant - Mass flow rate

e) Current and voltage (Heater)

f) Current and voltage (Compressor) – turning the selector.

g) Motor speed.

iii. For the spring scale, level the arm to the pointer. Record the initial value of it.

iv. Turning the water control valve on the flow meter to get the desire flow rate.

v. Switch ON the compressor.

vi. The spring scale now will move down and not level to the pointer. Loose the knob and pull the holder to adjust back to previous position.

vii. Let the machine to run about 10 minutes.

viii. After 10 minutes, records down all the reading.

ix. Let the machine to stable in 10 minutes before start the other experiment.

x. The first experiment can be test with others cooling load by switch ON the heater and adjust the heat power regulator to get to desired power.

xi. By refer to the R 134a properties table, get the values of the specific entropy and specific enthalpy to plot the graph of T-s and P-h diagram.

5.3 Experiment Data

Initial ValueHeater Voltage, V1

Heater Ampere, A1

T1T2T3T4T5T6Motor Voltage, V2

Motor Ampere, A2

Force (N)Pressure (P1)Pressure (P2)Motor Speed, (RPM)Mass Flow Rate