Analysis and comparison of innovative PEMFC systems coupled with an ASHP for space heating in cold climates

Abstract

In this study, two integrated systems are proposed and analysed: an air source heat pump (ASHP) coupled with either high-temperature proton exchange membrane fuel cells (HT-PEMFCs) or low-temperature proton exchange membrane fuel cells (LT-PEMFCs), where the exhaust gases from the PEMFCs are used to increase the external air temperature to the evaporator of the ASHP. The objective is to understand how the proposed systems behave in a cold climate region and determine which of the systems is better to couple with an ASHP for domestic space heating purposes in a cold climate. The novelty of the work lies in the idea of recovering heat from the exhaust gases from the fuel reformer and PEMFCs and mixing them with external air, before sending it to the ASHP as the inlet air. Grey-box models are employed to model the PEMFCs, whereas the hypothesis of the chemical equilibrium of reacting species is considered in the reformer model. Steady state analyses are considered to understand the performances of the proposed systems compared to two different types of furnaces: high-efficiency and mid-efficiency ones. The results indicate that the HT-PEMFCs are the best for the case studied here, with performances up to 100% greater than the mid-efficiency furnace and up to 63% more than the high-efficiency one. A scenario analysis on a simple pay back is also carried out, and the return on the investment costs in the 2024 scenario is about 24 years if compared to the high efficiency furnace and 14 if compared to the mid-efficiency one, whereas the corresponding numbers are 19 and 11 years, respectively, for the 2030 scenario.