UNIVERSITY INSTITUTE OF ENGINEERING

DEPARTMENT OF MECHANICAL ENGINEERING

REFRIGERATION & AIR CONDITIONING LAB (MEY-303)

Experiment No. 3
Aim: To evaluate the performance of domestic air conditioner.

List of Equipment Used:

Table 3.1: List of Equipments
S.N. Equipment Range Quantity
1. Power supply Single Phase, 220 V 1
2. Socket with earth connection 5-15 amp 1

Introduction:

Air conditioning is the simultaneous control of the temperature, humidity, motion and purity of
the atmosphere in a confined space. Air conditioning applies in the heating season as well as in
the cooling season. TheAir conditioning has wide applications in submarine ships, aircrafts and
rockets. Air conditioning is associated with the human comfort and controlling the humidity
ratio.

Theory:

Air conditioning 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. This is widely used for cooling of
storage chambers in which perishable foods, drinks, and medicines are stored. Figure shows the
schematic of the unit with complete description.
 UNIVERSITY INSTITUTE OF ENGINEERING

DEPARTMENT OF MECHANICAL ENGINEERING

REFRIGERATION & AIR CONDITIONING LAB (MEY-303)

Figure 3.1: VC cycle components

Compressor:

The main function of compressor is to raise the pressure and temperature of the
refrigerant by the compression of the refrigerant vapour and then pump it into the
condenser.

Condenser:

Condense the high pressure vapour refrigerant into the high pressure liquid by condenser
fan and passes it into the receiver tank for recirculation

Capillary tube:

Expands the liquid refrigerant at high pressure to the sub cooled liquid refrigerant at low
pressure so that a measured quantity of liquid refrigerant is passed into the evaporator.
 UNIVERSITY INSTITUTE OF ENGINEERING

DEPARTMENT OF MECHANICAL ENGINEERING

REFRIGERATION & AIR CONDITIONING LAB (MEY-303)

Evaporator:

Evaporates the sub cooled liquid refrigerant by absorbing the sensible heat into vapour
refrigerant and sends back into the compressor.

Vapour compression cycle:

The refrigerant starts at some initial state or condition, passes through a series of
processes in a definite sequence and returns to the initial condition. This series of
processes is called a cycle.

Figure 3.2: Standard vapour compression cycle (svcc):

The Standard Vapour Compressor Cycle (SVCC) consists of the following processes:

• Reversible adiabatic compression from the saturated vapour to a super-heated

condition.

• Reversible heat rejection at constant pressure (sub cooling liquid and condensation of
the refrigerant)
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DEPARTMENT OF MECHANICAL ENGINEERING

REFRIGERATION & AIR CONDITIONING LAB (MEY-303)

• Irreversible enthalpy expansion from saturated liquid to a low pressure sub cool liquid.

• Reversible heat addition at constant pressure.

Coefficient of performance (c.o.p):

The coefficient of performance of (C.O.P.) of a refrigerating cycle is defined as the ratio

between net refrigeration (output) and compressor work (input).

COP = RE/ CW

RE=H1 −H4

CW=H2 −H1

C.O.P= (H1–H4) / H2–H1

Description:

The window air-conditioning test rig unit is required to conduct experiments and demonstrate
the processes of cooling of atmospheric air. The unit consists of a compressor. Both evaporator
and the air cooled condenser are mounted on board with separate fans. Air is sucked from the
room and is supplied to the room after cooling. The system is provided with energy meter, a
digital temperature indicator. The unit will be fitted with all instrumentation facilities so that
temperature and pressure can be measured at different points in the air-conditioning system.

Experimental procedure:

Starting procedure:

1 Close valves of pressure gauges.

2 Switch ‘ON’ the main power supply.

3 Switch ‘ON’ the compressor.

4 Wait for 2-3 minutes for switch ‘ON’ the compressor.

5 Open the valves of pressure gauges.

6 After 10 minutes note down the reading of temperature sensor.

 UNIVERSITY INSTITUTE OF ENGINEERING

DEPARTMENT OF MECHANICAL ENGINEERING

REFRIGERATION & AIR CONDITIONING LAB (MEY-303)

7 Note down the reading of pressure gauges.

8 Note down the voltage & ampere.

9 Repeat steps 6 to 9 after every 10 minutes till the temperature of outlet of air come
constant.

Closing procedure:

1 Switch ‘OFF’ the compressor.

2 Switch ‘OFF’ the mains.

Observation & Calculations:

8.1 OBSERVATION TABLE:

Sr. P1 P2 T1 T2 T3 T4 T5 T6 V I
No. (kg/cm2) (kg/cm2) (°C) (°C) (°C) (°C) (°C) (°C) (Volts) (Amp)

Calculations:

H1 = (0.011×T1 −1.98)P1+ (0.652×T1) + 415.723

H2 = (0.011×T2 −1.98)P2+ (0.652×T2) + 415.723

H4 =1.228×T3 +199.93 (H3 =H4)

C.O.P = H1 –H4

H1 −H 2
 UNIVERSITY INSTITUTE OF ENGINEERING

DEPARTMENT OF MECHANICAL ENGINEERING

REFRIGERATION & AIR CONDITIONING LAB (MEY-303)

Nomenclature:

Nom. Column Heading Units Type

C.O.P. Co-efficient of performance for compressor * Calculated

P1 Pressure at compressor suction kg/cm2 Measured

P2 Pressure at compressor discharge kg/cm2 Measured

T1 Temperature at compressor suction °C Measured

T2 Temperature at compressor discharge °C Measured

T3 Temperature at condenser outlet °C Measured

T4 Temperature at evaporator inlet °C Measured

T5 Temperature of air at inlet of duct °C Measured

T6 Temperature of air at outlet of duct °C Measured

H1 Enthalpy of refrigeration effects at kJ/ kg Calculated

compressor inlet

H2 Enthalpy of compressor work at compressor kJ/ kg Calculated

outlet
 UNIVERSITY INSTITUTE OF ENGINEERING

DEPARTMENT OF MECHANICAL ENGINEERING

REFRIGERATION & AIR CONDITIONING LAB (MEY-303)

H3 Enthalpy of sub cooling at the outlet of kJ/ kg Calculated

condenser

H4 Enthalpy of refrigerant inlet of evaporator kJ/ kg Calculated

I Ampere meter reading Amps Measured

V Voltmeter reading Volts Measured

Precaution & maintenance instructions:

10.1 Operate the Valves gently.

10.2 Never run the apparatus if power supply is less than 180 volts and above 230 volts.

10.3 Duct should be free from dust particles.

Result(s): COP of the vapour compression refrigeration system

Review Questions

Q1 What is COP?

Q2 What is VC cycle?

Q3 Explain various components of VC cycle

Q.4 what are pychrometric processes?

 UNIVERSITY INSTITUTE OF ENGINEERING

DEPARTMENT OF MECHANICAL ENGINEERING

REFRIGERATION & AIR CONDITIONING LAB (MEY-303)

Prepared By- Reviewed By- Approved By-

Vishal Mahajan Dr. Gurpinder Dhindsa Dr. Ishbir Singh