A review of heat pump systems for heating and cooling of buildings in China in the last decade

Abstract

a b s t r a c tHeat pump technology fully shows the principle of energy recycling in terms of Heating, Ventilating and Air Conditioning (HVAC). It avoids unipolarity of energy using in the conventional HVAC system. Heat pumps use high-grade energy as a driving energy, recovering and upgrading low-grade energy for avail, like a pump. Because heat source used in HVAC usually is low temperature heat, heat pump systems adopted in HVAC will help improve heating performance coefficient. Therefore, HVAC is one of ideal users of heat pump applications, and thus high-grade energy used in HVAC can be replaced with a large number of low-temperature renewable energy. Through the heat pump technology, natural low-grade energy stored in the soil, water, air or waste heat from variant industries and daily lives, is supplied for building cooling/heating and hot water serving. Therefore, vast applications and developments of heat pump technology are presented in HVAC in China, and some progresses are achieved in the system innovation, experimental research, product development and engineering application, etc. This paper reviews the progress of researches, applications and development in the field of heat pumps for building cooling/heating in China since the 21st century.

Analysis of the Potential of Low-Temperature Heat Pump Energy Sources

“…The energy transferred from the air to the heat pump evaporator returns to the environment as thermal losses of the building. However, according to literature [1][2][3], the operation of the system is not efficient, reliable, nor stable during winter when the outdoor temperature is low. The exploitation of surface or groundwater is limited, in particular, by its availability, complex legislation, water flow variability and instability of the energy potential [4].…”

Laboratory investigations and numerical analysis of thermal performance of the single U-tube VBHE in multiple-layer substrates

“…GSHP technology uses shallow geothermal energy, and converts low-grade thermal energy in the ground into high-grade energy to achieve the purpose of energy conservation (Luo et al, 2016;Ni et al, 2015;Yang et al, 2010). The vertical buried heat exchanger (VBHE) has been common in the GSHP system, and it is one of the most important parts in the system.…”

An experimental study on defrosting performance for an air source heat pump unit with a horizontally installed multi-circuit outdoor coil

“…[4]. Accordingly, as a key type technology under clean development mechanism (CDM) to mitigate the climate change and avoid global warming [5], it becomes widely used as cooling and heating sources for heating, ventilation and air conditioning over the recent decades [6]. However, on its heating mode of an ASHP unit under extremely cold and high humidity environment, unexpected frost would appear and accumulate over the outdoor coil's airside surface, which severely deteriorates system operating performance.…”

“…1(e) and 1(f), when the installation type of the three-circuit outdoor coil is changed, 6 the total area of retained water is increased, from 590 mm × 44 mm to 590 mm × 500 mm, being increased 11.36 times. Therefore, it is contradictory for the maximum flow path of melted frost and the total area of remained water on improving system defrosting performance.…”