The condenser operates according to its own rules, but it is also a part of the refrigeration system and therefore interacts with the other components. Except in the low-condensing temperature regions where certain operating limits may apply, it is always desirable to operate at as low a condensing temperature as possible. But, as Fig. 7.35 shows, an increase m the refrigeration load increases the condensing temperature in order to transfer a higher heat flow rate.
It is unfortunate that the condensing temperature increases and the compressor power per unit refrigerating capacity increases at just the time when the refrigeration rate is high. Figure 7.35 also shows that the condensing temperatures can be lowered at all ranges of refrigeration load if a large condenser is chosen. Certainly there would be additional first cost associated with the larger condenser, and perhaps additional fan power, but the compressor power drops throughout its life. A further advantage of the large condenser with its lower condensing temperature is that the peak refrigerating capacity of the compressor can be increased slightly.