Study On Heat Storage Performance And Thermoelectric Conversion Of Salt-gradient Solar Pond

Nowadays such problems as shortage of resources,environmental pollution are increasingly serious,the development and utilization of new energy is imminent.Solar pond as a simple technological,economical suitable,clean and pollution-free solar collector has received more and more attention.In this paper,we constructed a variety of solar ponds to study the heat storage performance of the solar pond with different types of turbidity,working fluid,shape and layer structure.According to the output characteristic of the thermoelectric module,the integrated structure of the solar pond and the thermoelectric module was set up,so as to realize the thermoelectric conversion of solar energy.Specific works are as follows:(1)When the turbidity of the solar pond is higher,the bottom temperature is lower,so it is not conducive to heat storage.Polyaluminium chloride with strong activity flocculant has a better effect of descending the turbid,and the effect can keep for a long time.Compared to heat storage performance of NaCl,CaCl2,MgCl2,MgSO4,Na2CO3 and imitation bittern solution,the higher relative molecular mass,the smaller specific heat capacity and the greater the solubility of the refrigerant can make the heat storage performance of solar pond better.We made a circular and a square solar pond with cross sectional area 625 cm2,height 20 cm,respectively.We measured the temperature with different height of the two kind of solar ponds,and calculated the heat storage,the results show that the bottom temperature,the absorption of heat and energy efficiency of the circular solar pond were higher than the square solar pond.(2)The results of the study revealed that the more non-convective layers could decrease the transmittance of the solar radiation.Although that could make the solar pond instantaneous heat collection effect reduced,the heat storage effect of solar pond in lower convective layer could be better,and could also be beneficial to maintain the salinity and the turbidity of the solar pond.For the design of the lower convective zone,it reflected that as the bottom salinity increasing,the more heat could be stored but the stability of salt gradient was worse at the same number of layers.We also set asphalt concrete residue and boiler slag two kind of industrial waste in the bottom of the pond.It found out that the bottom temperature of asphalt concrete group is higher,and has better heat-insulating performance.In addition the solar pond with boiler slag had better stability in salt gradient.So selecting the materials of large porosity,small thermal conductivity,high specific heat capacity in the bottom of the solar pond was favorable for improving the temperature and stability.(3)For the study of solar pond thermoelectric conversion applications,this paper designed a thermoelectric module structure to study its output characteristics.The results showed that the short circuit current and open circuit voltage of the thermoelectric power generation sheets were both increased with the increased number of the thermoelectric sheets.At the same temperature,open circuit voltage thermoelectric power generation sheets in series connections are better than an equivalent number of thermoelectric power generation sheets in parallel connected;short-circuit current thermoelectric power generation sheets in parallel connections are better than an equivalent number of thermoelectric power generation sheets in series connected.