Test Rig Vapour Compression and Refrigeration Cycle Study
Refrigeration Test Rig Instruction Manual
OBJECTIVE:-
To study Refrigeration test rig and to study the vapour compression refrigeration cycle
AIM:-
To calculate co-efficient of performance and draw P-H diagram.
INTRODUCTION:-
Room air conditioner is based on vapour compression cycle: Out of all refrigeration system, the vapour compression system is the most important system from the view point of commercial and domestic utility. It is the most practical form of refrigeration. In this system the working fluid. Is a vapour. It readily evaporates and condenses or changes alternatively between the vapour and liquid phases without leaving the refrigeration plant. During evaporation, it absorbs heat from the cold body. This heat is used as its latent heat to external body, thus creating a cooling effect in the working fluid. this refrigeration system thus act as a latent heat pump since it pumps its latent heat from the cold body or brine and rejects it or delivers it to the external hot body or cooling medium.
VAPOUR COMPRESSOR:
The refrigerant start at some initial state or condition passes through a series of processes in a definite sequence and return to the initial condition. This series of processes is called cycle.
The standard vapor compressor cycle (SVCC) consists of the following processes:
- 1-2 reversible adiabatic compression from the saturation vapor to a super heated condition (electrical) input.
- 2-3 reversible heat rejection at constant pressure (de-superheating and condensation of the refrigeration)
- Irreversible is enthalpy expansion from saturated liquid to a low-pressure vapor.
- Reversible heat addition at constant pressure.
COMPRESSOR
The main function of compressor is to raise the pressure and temperature of the refrigerant by the compression of the refrigerant vapor and then pump it into the condenser.
CONDENSER:-
Condense the vapor refrigerant into the liquid by condenser fan passes it into the receiver tank for re-circulation.
OBERVATION:-
S No P1 P 2 T1 T2 T3 T4 V I
1
2
3
CALCULATIONS:
Mark points 1, 2, 3 using (P1, T1), (P2, T2),(P2,T3) respectively on P-h diagram for (R-134a) and read H1, H2 and H3 (where H3 = H4) to calculate COP.
(C.O.P)TH =
m=
UTILITIES REQURIED:
1. Electricity Supply: Single Phase, 200 VAC, 50Hz, 5-15Amp socket with earth connection.
EXPERIMENTAL PROCEDURE:
- Clean the apparatus and make it free from dust.
- Ensure that all ON/OFF switches given on the panel are at OFF position.
- Now switch ON the main Power supply.
- Ensure that all valves are open position.
- Now switch ON the compressor.
- After the gap of 10 or 15 minutes take the reading of pressure gauge, voltmeter, ampere meter and T1, T2, T3, and T4 by digital temperature indicator.
OBERVATION & CALCULATION:
Data
Cos = 0.8
Pw = 1000kg/m3
Cp = 4.186kj/c
———————————-
NOMENCLATURE:
= Destiny of water, kg/m2
Cos = Power factor
Cp = Specific heat of water, kJ/kg 0C
(C.O.P.)Rel = Relative coefficient of performance.
(C.O.P.)Th = Theoretical co- efficient of performance.
(C.O.P)Act = Actual co- efficient of performance.
CW Th = Theoretical compression work kJ/sec.
CW Act = Actual compression work kJ/sec
H1 = Enthalpy of refrigeration effects at compressor inlet,
kJ/kg.
H2 = Enthalpy of compressor work at compressor inlet, kJ/kg.
H3 = Enthalpy of sub cooling at the outlet of condenser, kJ/kg.
H4 = Enthalpy of refrigerant inlet of evaporator, kJ/kg.
P1 = Pressure at compressor suction, kJ/cm2.
P2 = Pressure at compressor discharge, kJ/cm2
RE Th = Theoretical refrigeration effect kJ/sec.
RE Act = Actual refrigeration effects kJ/sec.
T1 = Compressor inlet temperature, 0C
T2 = Compressor outlet Condenser inlet temperature, 0C
T3 = Condenser outlet temperature, 0C
T4 = Water temperature, 0C
t = Time, sec
I = Ammeter reading, Amps.
V = Voltmeter reading, volts
Vwe = Volume of water in evaporator, ltr.
m = mass of water, kJ/kg.
PRECAUTIONS & MAINTENANCE INSTRUCTIONS:
- Never run the apparatus if power supply is less than 180 volts and above 230 volts.
TROUBLESHOOTING:
- If electric panel is not showing the input on the mains light, check the main supply.