The effects of subcooling and superheating in refrigeration system
MM321 REFRIGERATION AND AIR CONDITIONING
LAB 3
The Effects of Subcooling and Superheating
Name: Ameniasi Naiqamu
ID: S11051703
Date: 20/08/2013
Aim:
To observe the effect that occurs in a refrigeration system when it undergoes Subcooling and Superheating.
Introduction:
Process Involved:
Process 1-2 Isentropic Compression
Process 2-3 Constant Pressure heat rejection
Process 3-4
Isenthalpic process therefore;
Process 4-1 Constant Pressure heat absorption inside the evaporator
Coefficient of Performance is given by;
Some factors that affect the Coefficient of Performance of the refrigeration are;
Sub Cooling of liquids
Superheating of Vapor (May be constant, increase or decrease)
Change in suction pressure
Change in discharge pressure
Effect of volumetric efficiency of Compressor [2].
Methodology:
Firstly, the mass flow rate of the refrigeration cycle was determined in order to get steady values of results. Secondly, the values of temperature were recorded for the different points corresponding to the P-h chart. Once the temperature was found, it is plotted in the P-h chart to determine the values of enthalpy for the respective points. Compared the ideal values of COP with the actual values and note the significance.
Apparatus:
Refrigeration Cycle
Results:
Values
Mass Flow Rate
1 bar
5bar
40g/s
Data obtained from reading the P-h chart.
Figure 1.0 P-h chart outline
Values
Calculation of COP
A) Ideal
B) Actual – Superheated Region
> Increase in Compressor work > Increase in Refrigeration Effect
>
Discussion:
It was noted from the above solution that the true value of COP obtained from the experiment was 4.875. The ideal value of COP as obtained directly from the P-h chart would correspond to 4.81. Also, the work of the compressor is high with superheating i.e. ( ) and is greater than the ideal
LAB 3
The Effects of Subcooling and Superheating
Name: Ameniasi Naiqamu
ID: S11051703
Date: 20/08/2013
Aim:
To observe the effect that occurs in a refrigeration system when it undergoes Subcooling and Superheating.
Introduction:
Process Involved:
Process 1-2 Isentropic Compression
Process 2-3 Constant Pressure heat rejection
Process 3-4
Isenthalpic process therefore;
Process 4-1 Constant Pressure heat absorption inside the evaporator
Coefficient of Performance is given by;
Some factors that affect the Coefficient of Performance of the refrigeration are;
Sub Cooling of liquids
Superheating of Vapor (May be constant, increase or decrease)
Change in suction pressure
Change in discharge pressure
Effect of volumetric efficiency of Compressor [2].
Methodology:
Firstly, the mass flow rate of the refrigeration cycle was determined in order to get steady values of results. Secondly, the values of temperature were recorded for the different points corresponding to the P-h chart. Once the temperature was found, it is plotted in the P-h chart to determine the values of enthalpy for the respective points. Compared the ideal values of COP with the actual values and note the significance.
Apparatus:
Refrigeration Cycle
Results:
Values
Mass Flow Rate
1 bar
5bar
40g/s
Data obtained from reading the P-h chart.
Figure 1.0 P-h chart outline
Values
Calculation of COP
A) Ideal
B) Actual – Superheated Region
> Increase in Compressor work > Increase in Refrigeration Effect
>
Discussion:
It was noted from the above solution that the true value of COP obtained from the experiment was 4.875. The ideal value of COP as obtained directly from the P-h chart would correspond to 4.81. Also, the work of the compressor is high with superheating i.e. ( ) and is greater than the ideal
References: [1]. Cengel, Y.A. and Boles, 2011, Thermodynamics – An Engineering Approach, McGraw Hill, Chicago. [2] Prof. T. Sundararajan and Prof. J.M. Mallikarjuna., Refrigeration Cycles, viewed 15 August 2013, http://nptel.iitm.ac.in/courses/IIT-MADRAS/Applied_Thermodynamics/Module_6/6_Simple_Vapor_Compression_RS.pdf.