The effect of condensation temperature on capacity
The condensation temperature of the refrigerant is considered to be 6°C – 20°C above air inlet temperature for general purposes. The condensation temperature varies according to the ambient temperature in which the system will operate. This said, the condensation temperature for applications is commonly taken as 30- 60°C.
Factors taken into consideration for determining the condensation temperature: Ambient temperature,
Thermophysical properties of the refrigerant
Properties of the selected compressor
And the dimensions of the condenser.
While providing the nominal condenser capacity in condensers as per the Eurovent Standard, the air inlet temperature and condensation temperature are taken as 25°C and 40°C respectively. In other words, T = 15 °C.
A low value should be selected for the temperature differential T, in places of high ambient temperature. For instance, while designing for the conditions of Antalya the T value should be selected within the range of 7°- 10° C. For systems that will operate in outdoor environments in conditions of Turkey, the temperature differential should be lowered as one goes from the north to the south and selections should be made accordingly. It must always be considered that High Compression Temperature creates a load on the compressor that reduces efficiency and shortens its useful life. It will be quite beneficial in the design for the condensation temperature to be specified as low as possible. However, in some conditions it is not possible to take a low value for the condensation temperature. For example in Middle East countries where the outdoor temperature is 50°C-55°C, high condenser temperature is unavoidable.
The condensation temperature of the refrigerant is considered to be 6°C – 20°C above air inlet temperature for general purposes. The condensation temperature varies according to the ambient temperature in which the system will operate. This said, the condensation temperature for applications is commonly taken as 30- 60°C.
Factors taken into consideration for determining the condensation temperature: Ambient temperature,
Thermophysical properties of the refrigerant
Properties of the selected compressor
And the dimensions of the condenser.
While providing the nominal condenser capacity in condensers as per the Eurovent Standard, the air inlet temperature and condensation temperature are taken as 25°C and 40°C respectively. In other words, T = 15 °C.
A low value should be selected for the temperature differential T, in places of high ambient temperature. For instance, while designing for the conditions of Antalya the T value should be selected within the range of 7°- 10° C. For systems that will operate in outdoor environments in conditions of Turkey, the temperature differential should be lowered as one goes from the north to the south and selections should be made accordingly. It must always be considered that High Compression Temperature creates a load on the compressor that reduces efficiency and shortens its useful life. It will be quite beneficial in the design for the condensation temperature to be specified as low as possible. However, in some conditions it is not possible to take a low value for the condensation temperature. For example in Middle East countries where the outdoor temperature is 50°C-55°C, high condenser temperature is unavoidable.
The following example shows the compressor absorbed power at various condensation temperatures and the achieved cooling capacities for a semi-hermetic type HGX4/555-4 model compressor manufactured by BOCK, which uses R134A gas (Table 1). The cooling gas selected for the example is R134A. As seen from the table, when the condensation temperature rises from 30°C to 60°C, the compressor draws 25% more power while the cooling capacity drops by 38.5%, the COP value (ratio of the cooling capacity to the power drawn by the compressor) decreases by 51% and the a unit that is 38.5% larger must be used to achieve the cooling capacity declared in the design.
Condensation Temperature (°C)
Evaporation Temperature (°C)
Cooling Capacity (W)
Power Drawn by the Compressor (kW)
Cooling Capacity / Power
Drawn by the Compressor
30
-5
21,997
5.93
3.71
40
-5
19,665
6.49
3.03
50
-5
16,876
6.99
2.41
60
-5
13,545
7.43
1.82
70
-5
9,586
7.82
1.23
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