Increasing the Heat Utilisation Factor by Advanced Heat Recovery Techniques

Heat pumps-based technology is used among several relevant applications, to increase the heat
utilisation factor for power plants based on low-grade heat recovery. The technique to implement the
heat recovery system based on heat pump technologies uses the reverse Brayton cycle (RBC)
Ferreiro [29], Ferreiro et al. [30], and patent references P1-P9. The RBC exhibits an inherent
characteristic consisting of transfer heat from a cold environment to a hotter one while delivers some
mechanical work, so that contributes to the efficiency enhancement.
Since the technologies involved in advanced heat recovery techniques deals with combined cycle
based recovery technology, some antecedents concerning combined cycle technologies must be
revised. Thus, Fig. 10.1 and Fig. 10.2 depicts two combined thermal cycles. In the first shown in
Fig. 10.1, a Brayton cycle is combined with a Rankine cycle. This is referred to a conventional
combined cycle, while in the second one shown in Fig. 10.2, a heat pump based 0n a RBC is
combined with a non-conventional thermal engine, (the described XCPs), where the heat pump,
assuming the function of a primary or topping cycle consists of compressor, expander and two heat
exchangers, responsible for the heat source and the heat sink of a secondary or bottoming cycle
implemented under XCP technology.