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164 results on '"Zheng, Wandong"'

20. Thermal comfort evaluation of natural convective-radiant evaporator for air conditioning.

Author

Zhang, Huan, Zhao, Rui, Tao, Ming, and Zheng, Wandong

Subjects
AIR conditioning, HEAT radiation & absorption, HEAT pumps, HUMAN comfort, HUMIDITY, THERMAL comfort
Abstract

The radiant systems come to the fore due to energy saving potential and good integration. The effect of different forms of cold surfaces on human thermal comfort is focused on its application. A novel natural convection-radiant evaporator for heat pumps was developed and its influence on thermal comfort was investigated. A numerical model of the chamber with the evaporator was established and verified with experimental results. Thermal comfort experiments were conducted in a climate chamber and the influence of its asymmetric and uneven cold radiation on the thermal comfort was investigated. Due to the limitation of PMV in uneven radiation situations, the revised predicted mean vote (RPMV) was proposed to assess the thermal comfort in asymmetric and uneven radiation environments based on experimental results. Based on RPMV, the influence of the surface area and temperature of the evaporator on thermal comfort was numerically analyzed. The results indicate that indoor air temperature and relative humidity, RPMV increase with the increase of plate temperature, but decrease with an increase in plate area. The most favourable indoor thermal comfort environment was obtained at an indoor air temperature of 28°C and relative humidity of 50%, which is 2°C higher than traditional air conditioning system. [ABSTRACT FROM AUTHOR]

Published
2024
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25. Study of the Performance of a Photovoltaic and Heat Pump Coupling System in a Low-Carbon Community.

Author

Cheng, Ling, Zhang, Sirui, Wang, Zhaoying, Li, Bin, Zhang, Huan, and Zheng, Wandong

Subjects
HEAT pumps, AIR source heat pump systems, HEATING load, EMISSIONS (Air pollution), ELECTRIC power distribution grids, HEATING
Abstract

Clean heating transformation and photovoltaic (PV) promotion gradually have become the keys to realize dual carbon strategy goals. Based on this, the combined application of building-integrated PV (BIPV) systems and air-source heat pump (ASHP) systems has received widespread attention. However, the current combined system still presents problems such as the mismatching in time between PV output and heating load. Therefore, in this paper, a novel BIPV and ASHP coupling system is proposed, and the operation parameters were optimized using low-carbon community as an example. A conventional PV and heat pump (HP) combined system, ASHP heating, and coal-fired heating were employed as the baseline and compared with the novel system. The results show that the optimized system can improve the PV power local accommodation rate by 43% compared with a conventional PV and ASHP coupling system. In terms of economic and environmental benefits, the operating cost of the optimized system is 50% of the cost of the ASHP system. Compared with coal-fired heating system, the annual air pollutant and carbon emissions can be reduced by 92% and 57%, respectively. The system also can improve the stability of power grid operation. The demand for power capacity can be improved by 62% and the annual load balance of the power grid can be improved by 29.5%. [ABSTRACT FROM AUTHOR]

Published
2024
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45. Multi-Objective Optimization with Active–Passive Technology Synergy for Rural Residences in Northern China.

Author

Zhang, Huan, Wang, Yajie, Liu, Xianze, Wan, Fujing, and Zheng, Wandong

Subjects
LIFE cycles (Biology), CARBON emissions, THERMAL comfort, HEAT pumps, CARBON cycle, VENTILATION, NATURAL ventilation
Abstract

Due to the serious problems with energy efficiency, carbon emissions, and thermal comfort of rural residences in northern China, an optimization of active and passive heating technologies for rural residences is necessary. In this paper, an optimization for rural residences in northern China is conducted with four objectives: the whole life cycle carbon emission; the annual energy consumption through heating, ventilation, and air conditioning systems; the annual cost; and thermal comfort. In addition, the optimization model with active–passive heating technology synergy is resolved by NSGA-II genetic algorithm. The active and passive design variables, including the type of air source heat pump, orientation, the type and thickness of envelope insulation, the layer of window glass, the window-to-wall area ratio, as well as sunspace parameters are preferred to obtain the optimal solution. The results indicate that the optimal solution obtained by the ideal point method gives the most outstanding performance. Compared with the prototype, the optimized carbon emissions in severe cold and cold regions decreased by 56.1% and 54.6%, respectively. The annual energy consumption decreased by 59.7% and 62.2%. Finally, the roof insulation thickness is the most sensitive design variable in Pareto-optimal solution sets. This paper offers significant guidance in the application of the optimization method of active–passive technology synergy to the energy-saving design of buildings. [ABSTRACT FROM AUTHOR]

Published
2024
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