Basic Research On Preparation And Application Of Microcapsule Phase Change Materials For Conventional Air Conditioning

In recent years,as conventional air conditioning systems are gradually becoming popular,which causes the grid load to rise and the user's operating costs to continue to improve.Airconditioning systems using thermal energy storage utiliaze the cold storage material to store the cold at off-peak electrical load period and uses it at the on-peak electrical load periods,thereby achieving the purpose ofshifts the on-peak demand to off-peak periods.However,it also has the problem of increasing energy loss due to heat exchange between various media during charging and discharging and the heat exchange performance of the conventional phase change material is poor.In order to solve the above problems,this paper introduces a microcapsuled phase change material slurry(MPCMS).microcapsuled phase change material(MPCM)suitable for conventional air conditioning conditions were prepared,and the best preparation process was selected and made into a stable MPCMS.MPCMS was applied to fan coil type conventional air conditioners and its heat transfer characteristics were studied:(1)A combination of monophase coagulation and crosslink emulsification process was used to prepare n-tetradecane/chitosan microcapsuled phase change material.The best preparation process was as follows:core-shell ratio 4:1,emulsifier dosage was PCM's 6%,the emulsifier type is OP-10/SDBS(mass ratio 1:1),and the stirring rate is 10000r/min.The optimum MPCM's latent heat is 123.7kJ/kg.The loading efficiency is 57.5%,the utilization rate is 71.8%,and the average particle diameter was 182.3?m.(2)Using sodium chloride aqueous solution as base fluid and Tween-80 as emulsifier,long-term stable MPCMS was prepared.Through stability test,when the concentration of NaCl solution was determined to be 5%,the emulsifier amount added is 4%by mass of MPCM,the MPCMS is most stable.(3)The viscosity of the MPCMS increases with the increase of the MPCM's mass concentration,the thermal conductivity of the suspension decreases with the increase of the mass fraction of the MPCM,and the viscosity of the MPCMS with the MPCM mass concentration of 25%is too large to be suitable for useing in air-conditioning system.(4)The cooling characteristics of the fan coil with MPCMS as the cooling water were numerically studied.The wind's temperature drop and the cooling capacity of the fan coil increase first and then decrease with the increase of the mass concentration of the MPCMS.The cooling capacity of the coil increase with the increase of the inlet flow rate and the decrease of the inlet temperature,but when the flow rate is too large or the inlet temperature is too low,the MPCM cannot be melted completely and cause the energy waste.