Optimization Of A Solar Heating System Combined With Dual-Source Heat Pump

Under the background of energy shortage and environmental problems, the solar energy has been paid more and more attention for it’s advantage of energy saving and environmental protection, especially in winter of the cold climate area such as northern places in China. A solar heating system combined with dual-source heat pump is a comprehensive utilization of solar energy and air energy for space heating. Both the system’s structure parameters and the control strategy of the system are considered for the optimization of the system based on an actual project which is included in this paper. The research results are of great significance to improve the efficiency and reliability of the system, reducing the energy consumption and improving the economic efficiency of the system. It can also provide theoretical reference for the future design of the same kind of heating engineering as well.Firstly, reling on a railway station building in the practical engineering, the simulation model of the solar heating system combined with dual-source heat pump is based on the platform of TRNSYS. According to the outdoor solar radiation intensity and the indoor heat demand conditions, the system operation modes is classified for different conditions it might met; the method of comprehensive efficiency is used as a solution to complete the system design of the area of collectors and storage tank volume and also other system components as well, on this basis, using orthogonal experimental design method to find out the influence of collector area, the collector azimuth, the collector inclination, flowrate of per unit collector area, storage tank volume of per unit collector area on the system performance, results showed that:the order of performance influence of the system that affected by the elements are as follows:the collector area> the collector azimuth> the collector inclination> storage tank volume of per unit collector area> flowrate of per unit collector area.Secondly, the model of system design parameters optimization is established using particle swarm algorithm, then build system optimization computing platform for system configuration parameters optimization,in this way making the heating system to meet the needs of the indoor heating demand while maximizing the use of solar energy collection at the same time. Taking a practical engineering solar-dual source heat pump heating system as an example, simultaneous optimization calculation results showed that the system of solar heating season total calories for maximum system design parameters are as follows:the collector azimuth is 14°, the collector tilting angle is 53°, the unit area of collector loop flow is 0.0149m3/(hr-m2), the unit collector area of storage tank volume is 0.146m3/m2, after synchronizing the selected parameters optimization, the energy suppliment of the water tank in heating season has an increase of 7.9% compared to the preliminary design.Finally, based on the system design parameters optimization, different system comtrol strategies which are the "maximum use of solar energy strategy (Strategy Ⅰ)" and "comprehensive utilization of solar energy and air strategy (Strategy Ⅱ)" are proposed, by comparing system performance to achieve the control strategy optimization of the system. Studies have shown that:when system comtrol strategy taking Strategy Ⅱ, the energy consumption of the heating system decreases with the increases of dual-source heat pump Switching control parameters Tq,when Tq equals to 10℃, the lowest energy consumption is reached, comparative studies have shown that the best strategy of system energy-saving operation is control strategy Ⅰ, its system COPs up to 4.35 in heating season; the system optimal control strategy in typical day operation results showed that:the system can be switched automatically according to indoor and outdoor conditions accurately achieve a variety of operating modes to verify the reliability of the control strategy. The typical day simulation data showed that when the system take the "maximum use of solar energy strategy (Strategy Ⅰ)", the energy that watertank supplied of the day accounted for 81% of building heating load, the COPs of the system is up to 4.76.