Experimental evaluation of a capillary heating bed driven by an air source heat pump and solar energy

Abstract

The traditional Chinese kang is a widely used domestic heating system in rural areas in northern China. However, such system could cause serious air pollution due to burning of biomass materials or coal. An improved bed heating system is introduced in this study to reform the traditional kang, using a capillary mat as a heating terminal, an air source heat pump (ASHP) and a solar energy as the heat source. An experimental prototype was built in a residential house in Xi’an, China, and tests were conducted to evaluate the system’s feasibility and performance under different operational modes. Results showed that the system could effectively provide an acceptable thermal environment for a separately heated room and with a reduced consumption of carbon-based fuel. When the system was completely driven by the ASHP, the daily electricity consumption of the ASHP is only 5.5 kWh with a supply water temperature of 40°C. When coupling the ASHP with the solar energy, the daily hours of solar energy utilization ranged from 3.5 to 4.5 h per day when the ratio of the solar thermal collector area to the floor area was approximately 1.0. The available ratio (days of utilized solar energy to the days comprising the full heating season) exceeded 66.0% over three heating seasons. The system was shown to be a feasible and energy-efficient heating strategy for rural buildings.

Thermal performance of a novel heating bed system integrated with a stack effect tunnel

“…Although the experimental house was not a real rural building, it has many characteristics of traditional rural residential buildings in northern China. 1 Figure 3 shows the plan layout is almost the same for both floors of the house. The experimental heating system was installed at the north-facing bedroom on the upper floor of the house, with an area of 11.9 m 2 .…”

“…This problem is especially more pronounced during the cold season. 1 More specifically, the air pollution originating from the heating is a major issue due to the health consideration during cold seasons in most cities in Northern China. Li et al.…”

“…In other words, the use of central district heating system in the rural areas could impose high costs associated with constructing a large-scale pipe network and the large ratio of heat loss through pipes leading to an inefficiency in the delivery of the heating to homes. 1 In order to resolve this shortcoming, the use of individual local heating system for key rooms or personal comfort systems are considered as an efficient and economical way to enhance thermal comfort of residents and to reduce the energy consumption of rural buildings in winter. 14–16…”

“…23 evaluated the performance of a solar hot water-driven Kang system in a passive solar house, and found that the daily mean air temperature in the test room was maintained above 18°C in 13 h. In order to resolve shortcomings of the solar energy system, including high vulnerability to the climate condition, to provide continuous heating, Su et al. 1 presented a heating bed system driven by an air source heat pump and the solar energy. They showed that the proposed system could utilize the clean solar energy and can be applied to provide continuous heating during cold seasons.…”

“…However, in the context of promoting the clean energy heating and improving the indoor air quality, the Chinese Kang is facing a serious challenge as this way of life may become obsolete. Based on previous studies, 1 the present study introduces an improved scheme for the traditional Chinese Kang. The developed system employs an air source heat pump to substitute the coal-fired or biomass directed-fired stove to provide a sustainable and controllable use of a clean energy source.…”