Analysis of heating performance of CO2 air-source heat pump in cold region
(2.Kunming Dongqi Corporation of Science and Technology, Kunming, Yunnan, China 650106)
【Abstract】CO2 air-source heat pump can operate stably in cold region, which is expected to be popularized and applied in the field of space heating. To evaluate the performance of CO2 air-source heat pump heating objectively and reasonably, the supercritical CO2 air-source heat pump heating system in cold region was built. According to outdoor ambient temperature and heating load, the heating period was divided into five different stages, and the heating operation parameters of CO2 air-source heat pump were adjusted in different stages. The results show that the CO2 air-source heat pump can meet the heating demand in cold region, and the average performance coefficient of the heating system in the heating periods can reach 2.236. At the same time, the heating room has good comfort. Taking coal-fired boiler and gas-fired boiler as reference, the energy utilization efficiencies and CO2 emission amounts of three kinds of heat source heating are compared and analyzed by using equivalent electricity method. The results show that the energy utilization efficiency of CO2 air-source heat pump heating is higher than that of gas-fired boiler heating and is slightly lower than that of coal-fired boiler heating after considering the energy grade. The CO2 emission amount of CO2 air-source heat pump heating is higher than that of gas-fired boiler heating, but 20.89% less than that of coal-fired boiler heating.
【Keywords】 supercritical CO2; fuel; measurement; space heating; air-source heat pump; energy utilization efficiency; CO2 emission amount;
(Translated by LIU T)
 China Lecture Hall. 2014–2018 Investigation Report of Urban Central Heating Market in China [R]. No. 690646, 2014 (in Chinese).
 TAMURA T, YAKUMARU Y, NISHIWAKI F. Experimental study on automotive cooling and heating air conditioning system using CO2 as a refrigerant [J]. International Journal of Refrigeration, 2005, 28 (8): 1302–1307.
 BERTSCH S S, GROLL E A. Two-stage air-source heat pump for residential heating and cooling applications in northern U. S. climates [J]. International Journal of Refrigeration, 2008, 31 (7): 1282–1292.
 MA Y T, DAI B M. Analysis of air-source heat pump for room heating [J]. Refrigeration and Air–Conditioning, 2013, 13 (7): 6–11 (in Chinese).
 XU J F, ZHAO Y H, QUAN Z H, et al. Defrosting characteristics and energy consumption of new air-water dual source composite heat pump system [J]. CIESC Journal, 2018, 69 (6): 2646–2654 (in Chinese).
 JIN C C, WANG R Z, ZHAI X Q, et al. Analysis of air source heat pump with small temperature difference fan-coil units for high efficient and comfort heating [J]. CIESC Journal, 2016, 67 (S2): 51–57 (in Chinese).
 SUN X P, GUO K Q, ZOU Z R, et al. System investigation of a solar combined with air-source heat pump system for greenhouse heating [J]. Acta Energiae Solaris Sinica, 2016, 37 (3): 658–665 (in Chinese).
 AFARIN A, RAKESH K, FUNG A S, et al. Experimental and simulation studies on air source heat pump water heater for year-round applications in Canada [J]. Energy & Buildings, 2018, 165: 141–149.
 LIU M, XUE K, ZHOU Y, et al. Night time performance analysis of air source heat pump heating system in Chongqing rural residential [J]. Journal of Civil, Architectural & Environmental Engineering, 2015, 37 (6): 87–97 (in Chinese).
 ZHANG J F, QIN Y, WANG C C. Review on CO2, heat pump water heater for residential use in Japan [J]. Renewable & Sustainable Energy Reviews, 2015, 50: 1383–1391.
 SCOCCIA R, TOPPI T, APRILE M, et al. Absorption and compression heat pump systems for space heating and DHW in European buildings: energy, environmental and economic analysis [J]. Journal of Building Engineering, 2018, 16: 94–105.
 SHIBUYA T, CROXFORD B. The effect of climate change on office building energy consumption in Japan [J]. Energy & Buildings, 2016, 117: 149–159.
 SATO K, KAWAZU Y, SAITOU T. Hot water supply and air conditioning system using CO2 heat pump: US8151586B2 [P]. 2012.
 WANG S, TOU H, CAO F, et al. Experimental investigation on airsource transcritical CO2, heat pump water heater system at a fixed water inlet temperature [J]. International Journal of Refrigeration, 2013, 36 (3): 701–716.
 HU B, WANG X, CAO F, et al. Experimental analysis of an air-source transcritical CO2, heat pump water heater using the hot gas bypass defrosting method [J]. Applied Thermal Engineering, 2014, 71 (1): 528–535.
 JIN D X, WANG P, KOYAMA S, et al. Effects of internal heat exchanger on performance of transcritical CO2 heat pump system [J]. Journal of Southwest Jiaotong University, 2012, 47 (4): 634–638 (in Chinese).
 ZHANG F Z, JIANG P X, LIN Y S, et al. Efficiencies of subcritical and transcritical CO2, inverse cycles with and without an internal heat exchanger [J]. Applied Thermal Engineering, 2011, 31 (4): 432–438.
 WANG S, TUO H, CAO F, et al. Experimental investigation on airsource transcritical CO2, heat pump water heater system at a fixed water inlet temperature [J]. International Journal of Refrigeration, 2013, 36 (3): 701–716.
 SONG Y, YE Z, CAO F. Climate adaptivity and field test of the space heating used air–source transcritical CO2 heat pump [J]. IOP Conference Series: Materials Science and Engineering, 2017, 232 (1): 012087.
 SONG Y, CAO F. The evaluation of the optimal medium temperature in a space heating used transcritical air-source CO2 heat pump with an R134a subcooling device [J]. Energy Conversion & Management, 2018, 166: 409–423.
 ZOU C M, CEN J W, LIU P, et al. Transcritical CO2 heat pump system with an ejector [J]. CIESC Journal, 2016, 67 (4): 1520–1526 (in Chinese).
 WANG W, LIU J D, SUN Y Y, et al. Key problems and countermeasures for air-source heat pump under whole working conditions in Beijing [J]. HV & AC, 2017, 47 (1): 20–27 (in Chinese).
 LIU M, SU H, ZHANG H F. Capillary floor radiant heating system of rural residential building in Chongqing [J]. Journal of Civil, Architectural & Environmental Engineering, 2014, 36 (s1): 75–78 (in Chinese).
 JIANG Y, LIU L B, YANG X. Discussion on different types of energy accounting methods in energy statistics [J]. Energy of China, 2006, 28 (6): 5–8 (in Chinese).
 JIANG Y, YANG X. The electricity equivalent method in energy evaluation [J]. Energy of China, 2010, 32 (5): 5–11 (in Chinese).
 HAMADA Y, MURAKAWA S, NAGAHIRO K, et al. Study on basic performance of CO2 heat pump water heaters and evaluation of defrosting cycle and reheating operation [J]. Transactions of the Society of Heating, Air-Conditioning and Sanitary Engineers of Japan, 2009, 34 (143): 47–59.
 ZHAO M, HU J, DAI J, et al. The accounting of CO2 emissions based on the energy balances [J]. Ecological Economy, 2012, 157 (11): 30–32 (in Chinese).
 DAI P, ZOU J Y, TIAN J, et al. Integrated optimization of CO2 emission mitigation in China power sector [J]. Automation of Electric Power Systems, 2013, 37 (14): 1–6 (in Chinese).
 XIE L. Research and prospects of energy consumption of thermal power generation in China [J]. Telecom Power Technology, 2016, 33 (1): 165–166 (in Chinese).
 YANG Y P, YANG Z P, XU G, et al. Situation and prospect of energy consumption for China’s thermal power generation [J]. Proceedings of the CSEE, 2013, 33 (23): 1–11 (in Chinese).