Comparison and Performance Analysis of Heat Storage Equipment in Solar Heating System

Solar heating system is widely used recently.Heat storage equipment is the guarantee for steady performance of solar heating system.A design of latent heat storage exchanger with submerged coil was introduced with the structure,working principle,and the main advantages.This heat exchanger was integrated into solar heating system as the heat storage equipment.Advantage comparison of the designed heat exchanger in solar heating system with hot water tank was carried out.The analysis results show that the latent heat storage exchanger is superior to hot water tank obviously.The heat exchanger performance parameters and variations of these parameters are got:(1)with the increase of phase change material(PCM)volume ratio,heat storage equipment volume ratio decreases;(2)heat storage efficiency has the same varying tendency with outdoor and air temperature;while the bigger PCM volume ratio is,the weaker the effect of outdoor air temperature on heat storage efficiency is;(3)heat storage capacity and heat storage efficiency increase together;when PCM volume ratio is big,heat storage efficiency is high and the system can begin operating efficiently and quickly;(4)with the increase of heat storage capacity,life cycle operation cost(LCOC)of system increases gradually in high speed;but with the increase of PCM volume ratio,the difference between the two systems LCOCs becomes smaller and smaller;(5)the reasonable range of PCM volume ratio is 0.5-0.7.Temperature characteristic analysis shows that,with the filled PCM,heat storage medium temperature presents several segments at different time,under conditions of different heat storage capacity and different PCM state.

Solar heating system is widely used recently. Heat storage equipment is the guarantee for steady performance of solar heating system. A design of latent heat storage exchanger with submerged coil was introduced with the structure, working principle, and the main advantages. This heat exchanger was integrated into solar heating system as the heat storage equipment. Advantage comparison of the designed heat exchanger in solar heating system with hot water tank was carried out. The analysis results show that the latent heat storage exchanger is superior to hot water tank obviously. The heat exchanger performance parameters and variations of these parameters are got： （1） with the increase of phase change material （PCM） volume ratio, heat storage equipment volume ratio decreases; （2） heat storage efficiency has the same varying tendency with outdoor and air temperature; while the bigger PCM volume ratio is, the weaker the effect of outdoor air temperature on heat storage efficiency is; （3） heat storage capacity and heat storage efficiency increase together; when PCM volume ratio is big, heat storage efficiency is high and the system can begin operating effcienfly and quickly; （4） with the increase of heat storage capacity, life cyde operation cost （LCOC） of system increases gradually in high speed; but with the increase of PCM volume ratio, the difference between the two systems LCOCs becomes smaller and smaller; （5） the reasonable range of PCM volume ratio is 0.5 - 0.7. Temperature characteristic analysis shows that, with the filled PCM, heat storage medium temperature presents several segments at different time, under conditions of different heat storage capacity and different PCM state.