The thermal analysis of a combined heat and power plant undergoing Clausius-Rankine cycle based on the theory of effective heat-absorbing and heat-emitting temperatures

Abstract In a combined heat and power plant (CHP plant), heat and power are produced simultaneously in the same power plant process. The CHP technology reduces total fuel consumption compared to a situation where heat and electricity are produced separately. For condensing power plants the exergy loss is usually calculated by multiplying the entropy generation rate with the real environmental temperature because the plant exchanges heat with the environment at the temperature close to this temperature. Instead, CHP plants emit heat into the environment at higher temperature level. The goal of this paper is to perform the Second Law analysis for a coal-fired CHP plant undergoing Clausius–Rankine cycle. The Second Law analysis is based on the use of effective heat-absorbing and heat-emitting temperatures. In this paper, temperatures are defined for a CHP plant undergoing Clausius–Rankine cycle. The maximum power to heat ratio of the CHP plant as well as entropy generation and power (exergy) losses are defined using the before mentioned temperatures instead of the real environmental temperature.