On-Vehicle Performance Comparison of an R-152a and R-134a Heat Pump System

Abstract

<div class="htmlview paragraph">As automotive power-train systems become more efficient, less waste heat is available for vehicle passenger cabin warming. As a result, alternative heating technologies are being investigated to alleviate this shortcoming. One alternative is to operate the existing A/C system in reverse (heat pump mode), thus providing supplemental heat.</div> <div class="htmlview paragraph">Recently, the environmental impact of refrigerant emissions has come under global scrutiny. The concern is their potential for global warming. Thus, the environmental characteristic of merit that makes for a more benign refrigerant in terms of emissions is lower Global Warming Potential (GWP). R-152a is a more environmentally benign refrigerant compared to R-134a with a GWP of 120 vs. 1,300 [<span class="xref">1</span>] and [<span class="xref">2</span>]. Both refrigerants are hydro-fluorocarbons - HFCs - (contain no chlorine) and hence, have zero ozone depletion potential.</div> <div class="htmlview paragraph">An environmentally benign refrigerant touted as a potential replacement for R-134a, is CO<sub>2</sub>. Analysis and experimental work [<span class="xref">3</span>, <span class="xref">4</span>] indicate great potential for trans-critical CO<sub>2</sub> systems operating in heat pump mode. The study of R-152a and R-134a heat pumps in this paper demonstrated similar results.</div> <div class="htmlview paragraph">This paper quantifies the heat pump capacity of R-152a and compares it to that of R-134a using engine coolant as a heat source. An actual production vehicle modified to have a heat pump system was used to demonstrate the performance in a climatic automotive wind tunnel.</div>