Experimental investigation on vapor injection ASHP for electric rail vehicles in cold region. (5th May 2019)

• Record Type: Journal Article
• Authors: Han, Xinxin; Zou, Huiming; Kang, Wei; Xu, Hongbo; Chen, Yiyu; Tian, Changqing
• Is Part Of: Applied thermal engineering. Volume 153(2019)
• Page Start: 473
• Page End: 482
• Publication Date: 2019-05-05
• Subjects: Vapor injection -- Air source heat pump -- Electric vehicle -- Heating performance; Heat engineering -- Periodicals; Heating -- Equipment and supplies -- Periodicals; Periodicals; 621.40205
• DOI: 10.1016/j.applthermaleng.2019.03.037
• Languages: English
• ISSNs: 1359-4311

Abstract

Highlights: A vapor injection air-source heat pump for electric rail vehicle was developed. The heating performance at ambient temperature −5 °C and −20 °C was experimentally investigated. The flow distribution characteristics between VI-branch and main-branch were obtained. The effect of injection ratio on COP was analyzed. Abstract: In this study, a vapor injection (VI) air-source heat pump (ASHP) for electric rail vehicles in cold region was developed and the heating performance at ambient temperature −5 °C and −20 °C was experimentally investigated. The effect of VI-branch electronic expansion valve (EEV2) opening on refrigerant flow distribution and heating performance of the system was analyzed. The mass flow rate of VI-branch increases with the increasing of EEV2 opening, and the main-branch mass flow rate also has increase about 9.1% at −5 °C and 12.3% at −20 °C because of the small change of inlet density of main-branch electronic expansion valve (EEV1). The ratio coefficients between the mass flow rate ratio and the pressure ratio of the VI-branch to the main-branch fitted from the experimental results are about 0.435 and the initial value is determined by the suction temperature and injection temperature. The maximum heating COP is 2.18 at the injection ratio of 0.18 under the condition of −5/15 °C and the maximum heating COP is 1.92 at the injection ratio of 0.29 under −20/15 °C, with 12.6% and 19.3% improvement of heating capacity compared with non-injection cycle. As the superheat of VI-branch is in the range of 5–10 °C, the COP gets a maximum.