1.1.4. Decomposing of complex refrigeration cycle

Decomposing a complex cycle into an assembly of simple vapor compression cycles is an alternative approach for predicting the power demand of a complex cycle. For example, a

Figure 2. (a) Multi-level refrigeration cycle—two heat sources and a single heat sink; (b) decomposition into simple cycles.

multi-stage cycle with multi-refrigeration levels and a single rejection level can be decomposed into simple cycles, as shown in Figure 2(b). The multi-stage cycle, such as the one shown in Figure 2(a), is decomposed into two simple cycles operating in parallel. One simple cycle operates between level 1 and ambient with cooling load given by the evaporator for level 1. The other simple cycle operates between level 2 and ambient with cooling load given by the evaporator for level 2 [2].

The decomposition approach constitutes a useful for the synthesis, analysis, and design of complex refrigeration system. The main advantage of decomposing approach is that power requirement can be predicted easily using a shortcut method and various design options can be screened quickly. However, some errors might arise when the complex cycle is compared with the decomposed simple cycles. This error is caused by the mixing effects at the inlet to the compressor in the case of a cycle with multiple refrigeration levels or the inlet to the expander for a multi-rejection level cycle [9].
