The Numerical Simulation And Energy-Saving Analysis Of The Solar Energy And Ground-Water Source Heat Pump Systems In Lanzhou

Both solar energy resources and groundwater resources are quite affluent in Lanzhou that is located in the northwest region. To make full use of these resources in Lanzhou can reduce the quantity of coal used and realize the requirement of environmental protection. This paper designs a supplementary heating system using solar energy and low temperature water-source heat pumps in this region via the combination of the technique of solar energy-thermal applications and heat pumps. Its operating conditions and the possibility of the extended application in this region are simulated numerically and analyzed in this paper, respectively.This paper adopts an office building in Lanzhou as a model of this heating system. Using a simulation tool package that is developed by Tsing-Hua University (Dest) for designing the building hot environment, the currently heating load of the building modeled during heating season can be calculated. The values of the maximal load and the currently maximal load can be obtained from the simulation results; a difference among them is about 11% or so. Terminal equipments can be determined by the former and the capacity selection of heat source depends on the latter. The processes of collecting heat, storing heat, supplementary heating, and releasing heat can be executed by the solar collectors of heat pipes and vacuum tubes, the hybrid water tanks of heat-storage, the low temperature water-source heat pumps, and heating terminal units (fan coils) in this system, respectively. Hence, the design requirement that keeps the indoor temperature constant can be met.According to the values of currently meteorological parameters and currently heating load, a supplementary heating system using solar energy and groundwater resources heat pumps can be designed and its operating conditions are simulated numerically by a simulation procedure compiled with C++Builder. In order to optimize the function of technique and economic performance of the supplementary heating system using solar energy and ground water resources heat pumps, a great deal of numerical simulation experiments and analysis are carried out from which the better values for the area of solar collectors of heat pipes and vacuum tubes, the thermal capacity of the water tanks of heat-storage, and the guaranteeing rate of solar energy heating are about 20.7 percent of the total construction areas of the building modeled,90L/m2, and 75.6 percent, respectively. These data can be considered as reference for design of the supplementary heating systems using solar energy and groundwater resources heat pumps in this region.Through its operating conditions, the comparison and analysis on economic performance among this system, the traditional central heating system, and electric film heating system are made by means of using of the system annual cost method. The results show that the running costs of this system is the lowest. The developing potential and economic competitiveness of the supplementary heating systems using solar energy and groundwater resources heat pumps can meet the requirements of heating systems in Lanzhou to some degree.