A New Mixture Refrigerant for Space Heating Air Source Heat Pump: Theoretical Modelling and Performance Analysis

Xiangrui Kong,Yufeng Zhang,Jinzhe Nie

doi:10.3390/app8040622

Abstract

Air source heat pump (ASHP) is becoming a substitute for small coal boilers in rural residential buildings of North China. However, the application of ASHP faces challenges of heating capacity, energy efficiency, ozone depletion potential (ODP) and global warming potential (GWP). Proper refrigerant is a key factor influences the performance of ASHP. In this paper, a new mixture refrigerant named RHR-1 is proposed, which aimed to improve energy efficiency, eliminate ODP and reduce GWP of ASHP refrigerant. The performance of RHR-1 was analyzed and compared with commonly used refrigerants including R134a, R410A, R407C and R22 in terms of heating coefficient of performance (COPh), compression ratio (CR) and discharging temperature (DT). The results show that, under the design cases, where supply water temperatures vary from 35 °C to 50 °C and outdoor air temperatures vary from −15 °C to 15 °C, the COPh of RHR-1 are in the range of 2.43–4.93. The COPh of RHR-1 is higher than other candidates when the supply water temperature is above 40 °C. The CR and DT of RHR-1 are in medium levels of the compared samples. A logarithmic regression equation was deduced to get the relationship of COPh with temperature difference between supply water and outdoor air which suggested the temperature difference should be controlled within 47.5 °C to get reasonable COPh. In addition, RHR-1 has no ODP, and its GWP is 279, which is much lower than other candidates. RHR-1 could be a reasonable refrigerant used in ASHP for space heating in North China.

Highlights

Due to air pollutant emissions such as particles, nitrogen oxides and sulfur oxides, coal and gas boiler heating systems were recognized as main causes of atmospheric pollution in North China which led to adverse impacts on human health [1,2,3]
Because the critical temperature of all refrigerant candidates are high enough to condense at 58 ◦ C, all the refrigerants are available choices to supply heating water at 50 ◦ C, but the COPh are quite different from each other
With RHR-1, R134a, R410A, R407C and R22 are in the ranges of 2.76–4.38, 2.73–4.41, 2.61–4.13, 2.60–4.13 and 2.77–4.39, respectively (Figure 8)

Summary

Introduction

Due to air pollutant emissions such as particles, nitrogen oxides and sulfur oxides, coal and gas boiler heating systems were recognized as main causes of atmospheric pollution in North China which led to adverse impacts on human health [1,2,3]. Air source heat pump (ASHP) is becoming a promising device for space heating in North China due to its energy-savings, environmental friendliness, and application flexibility [4,5]. Clean heating reform work and appointed to be a promoted substitution for existing small coal boilers in rural residential buildings of North China [5]. Sci. 2018, 8, 622 ; doi:10.3390/app8040622 www.mdpi.com/journal/applsci. Sci. 2018, 8, 622 still faces challenges such as heating capacity, frosting and low coefficient of performance (COP)

Methods

Results

Conclusion