Application of an alternative thermoeconomic approach to a two-stage vapour compression refrigeration cascade cycle

An alternative thermoeconomic approach is applied to a two-stage vapour compression refrigeration cascade cycle. This approach, called the UFS Model, is based on the splitting of the physical exergy into three terms, namely, internal energy term, flow work term and entropic term. Application of the UFS Model allows the isolation of both valves and condensers in the productive structure. The goal is to obtain the exergetic unit cost of each internal flow and plant product. This alternative approach yields consistent results, because exergetic unit costs are greater than or equal to 1 and the product-fuel ratio of each productive unit is less than or equal to 1. Besides the allocation of the external power cost of the plant, analyses on the irreversibilities of each cycle unit are carried out. Thus, it is shown that the UFS Model can also be used to quantify irreversibilities as well as the conventional exergy analysis.