Here we describe a heat pump system coupled with novel PV/T and thermal panels for space heating in low solar radiation conditions.Existing solar indirect-expansion systems connect the solar panels and evaporator of t...Here we describe a heat pump system coupled with novel PV/T and thermal panels for space heating in low solar radiation conditions.Existing solar indirect-expansion systems connect the solar panels and evaporator of the heat pump in parallel with the heat storage tank.For our system these three components are instead connected in series,which can stabilize the temperature at the inlet of the evaporator and decrease the inlet temperature of the solar panels,leading to improved energy efficiency and the production of much more thermal energy.The experimental results of this system show that the average electrical,thermal and overall efficiency of the PV/T panels are 15.9%,33.4%and 49.3%,respectively.The average thermal efficiency of the thermal panels is 60.4%,the COP of heat pump is 4.7 and the room temperature is constantly over 18°C.Based on the experimental results,some improvements are analyzed.We conclude that this operating model can meet the requirement of space heating in low solar radiation environments.展开更多
A mathematical optimization model was set up for a ground-solar combined system based on in-situ experimental results, in which the solar collector was combined serially with a ground-coupled heat pump (GCHP). The uni...A mathematical optimization model was set up for a ground-solar combined system based on in-situ experimental results, in which the solar collector was combined serially with a ground-coupled heat pump (GCHP). The universal optimal equations were solved by the constrained variable metric method considering both the per-formance and economics. Then the model was applied to a specific case concerning an actual solar assisted GCHP system for space heating. The results indicated a system coefficient of performance (COP) of 3.9 for the optimal method under the serial heating mode, and 3.2 for the conventional one. In addition, the optimum solution also showed advantages in energy and cost saving, leading to a 16.7% improvement in the heat pump performance at 17.2% less energy consumption and 11.8% lower annual cost, respectively.展开更多
A novel solar collector named dual-function solar collector(DFSC)has been proven feasible for supplying warm air for space heating in winter and hot water during none-heating season by theoretical and experimental stu...A novel solar collector named dual-function solar collector(DFSC)has been proven feasible for supplying warm air for space heating in winter and hot water during none-heating season by theoretical and experimental studies.While integrated with building,the DFSC becomes component of the envelope.Because complexly coupling of several heat transfer modes and subjecting to random weather condition,the thermal influence of DFSC on a building remains obscure.In order to investigate the effect of DFSC for passive and active heating,a demonstrating office building integrated with DFSC panels on the southern wall and roof has been built in Hefei,in the east region of China.A simulation project of the whole building system in winter was built by the software TRNSYS with the new component developed for DFSC and compiled into the TRNSYS library based on the validated theoretical method and experimental results from previous studies.The simulation results show that the energy supplied by the DFSC can meet the heating requirement at most of the time of a sunny day,except early morning.More than 30%solar fraction can be provided during the whole heating season in Hefei,the value further increases to 59%in a region of high solar irradiance,such as Lhasa.While active DFSC panels are operated to provide fresh warm air through ventilation system,the flow rate shows strong influence on the solar fraction of heating load.With appropriate operation scheme of the active DFSC,more energy savings and thermal comfort can be achieved.展开更多
文摘Here we describe a heat pump system coupled with novel PV/T and thermal panels for space heating in low solar radiation conditions.Existing solar indirect-expansion systems connect the solar panels and evaporator of the heat pump in parallel with the heat storage tank.For our system these three components are instead connected in series,which can stabilize the temperature at the inlet of the evaporator and decrease the inlet temperature of the solar panels,leading to improved energy efficiency and the production of much more thermal energy.The experimental results of this system show that the average electrical,thermal and overall efficiency of the PV/T panels are 15.9%,33.4%and 49.3%,respectively.The average thermal efficiency of the thermal panels is 60.4%,the COP of heat pump is 4.7 and the room temperature is constantly over 18°C.Based on the experimental results,some improvements are analyzed.We conclude that this operating model can meet the requirement of space heating in low solar radiation environments.
基金Supported by National Major Project of Scientific and Technical Programs of China During the 11th Five-Year Plan Period (No. 2006BAJ03A06)Tianjin Municipal Project for Science and Technology Development Plan (No. 06YFSYSF03600).
文摘A mathematical optimization model was set up for a ground-solar combined system based on in-situ experimental results, in which the solar collector was combined serially with a ground-coupled heat pump (GCHP). The universal optimal equations were solved by the constrained variable metric method considering both the per-formance and economics. Then the model was applied to a specific case concerning an actual solar assisted GCHP system for space heating. The results indicated a system coefficient of performance (COP) of 3.9 for the optimal method under the serial heating mode, and 3.2 for the conventional one. In addition, the optimum solution also showed advantages in energy and cost saving, leading to a 16.7% improvement in the heat pump performance at 17.2% less energy consumption and 11.8% lower annual cost, respectively.
基金supported by the National Natural Science Foundation of China(50978241)the National Basic Research Program of China(2011CB211703)
文摘A novel solar collector named dual-function solar collector(DFSC)has been proven feasible for supplying warm air for space heating in winter and hot water during none-heating season by theoretical and experimental studies.While integrated with building,the DFSC becomes component of the envelope.Because complexly coupling of several heat transfer modes and subjecting to random weather condition,the thermal influence of DFSC on a building remains obscure.In order to investigate the effect of DFSC for passive and active heating,a demonstrating office building integrated with DFSC panels on the southern wall and roof has been built in Hefei,in the east region of China.A simulation project of the whole building system in winter was built by the software TRNSYS with the new component developed for DFSC and compiled into the TRNSYS library based on the validated theoretical method and experimental results from previous studies.The simulation results show that the energy supplied by the DFSC can meet the heating requirement at most of the time of a sunny day,except early morning.More than 30%solar fraction can be provided during the whole heating season in Hefei,the value further increases to 59%in a region of high solar irradiance,such as Lhasa.While active DFSC panels are operated to provide fresh warm air through ventilation system,the flow rate shows strong influence on the solar fraction of heating load.With appropriate operation scheme of the active DFSC,more energy savings and thermal comfort can be achieved.
