Size Matching Consideration During Replacement Of Condensing Unit

Update:24 Jul 2017

In designing and constructing a RAC system with a relat […]

In designing and constructing a RAC system with a relatively small capacity, it is common practice to obtain a ready-to-use condensing unit directly and match it with an air or liquid cooler. This method is convenient because the prefabricated condensing unit usually completes the necessary piping between the compressor, the condenser, the oil separator and the accumulator. The system balancing task is also simplified because there is no need to balance each component one by one.

However, when it is necessary to replace the condensing unit of the existing system, it is not always possible to obtain exactly the same unit because the product is not burned due to, for example, the motor is burned out. If different units are selected, the system capacity and operating parameters must be carefully evaluated since the compressor and / or condenser size may be different and their dimensional relationship is fixed for a given unit. If the original dimensions of the new unit are suitable for different refrigerants, especially mixed refrigerants, further attention must be paid. It must be borne in mind that the catalog does not usually give information about the condenser's heat transfer area and compressor displacement, although the latter may be found in some catalogs.

In order to restore the system cooling capacity as needed in the latter case, it is necessary to know how the performance characteristics of the selected cells vary with the refrigerant already in the system. This information provides insight into how the overall system performance changes, helping to identify the appropriate cells from the catalog. However, for inexperienced engineers, changes in performance and charge requirements associated with existing systems are relatively difficult to specify in the catalog selection phase. Use computer simulations to select the meaning of the condensing unit from R22 or the list of refrigerant produced. The performance of an improved or upgraded system is discussed in the context of cooling capacity, refrigerant charge, and compressor power consumption variations. Although the analysis is based on a simplified water-to-water system, these findings are also generally applicable to air-cooled units. However, the document precludes oil and material compatibility considerations.