| In order to further reduce the energy consumption of cold storage and alleviate the serious pollution problem caused by over-exploitation and utilization of fossil energy to the environment,the application of solar photovoltaic refrigeration to cold storage systems,replacing fossil energy with renewable energy,is of great significance to reduce energy consumption and solve the environmental pollution problem.As the light conditions change in real time and are unstable and discontinuous,so solar refrigeration systems need to be paired with energy storage modules to solve the problem of unstable light conditions.Water tank energy storage has many advantages over battery and phase change material energy storage,so this paper proposes a water tank energy storage technology instead of traditional battery energy storage,and builds an energy storage cold storage system in parallel with vapor compression refrigeration system and driven directly by photovoltaic.Through TRNSYS software simulation,the system performance,cooling efficiency,storage efficiency and energy consumption of the PV storage cold storage system under different driving modes are investigated,and the feasibility and advantages of the operation of the PV storage cold storage system are analyzed,which provides an application form for replacing the traditional energy storage module with water tank storage.The paper also carries out the whole life cycle energy consumption and carbon emission accounting for the PV storage type cold storage,which further illustrates the practical and promotional value of the PV storage type cold storage system proposed in this paper from the perspective of carbon emission reduction.(1)Based on TRNSYS software,a load calculation model of PV storage type cold storage system was built to investigate the dynamic load variation of cold storage throughout the year by making detailed calculations of the dynamic load.The relationship between the operating performance of the cold storage system and the ambient temperature and light conditions is investigated.The settings and control conditions in the system model building process are adjusted according to the load variation characteristics to reasonably optimize the system modeling,ensure the matching of the supply,storage and discharge processes,and determine the best design solution.(2)According to the different driving sources of the cold storage system,three different driving modes are proposed: "direct driving by utility power","driving by utility power +cold storage tank",and "driving by photovoltaic + cold storage tank + utility power".Based on TRNSYS software,the system performance,cooling efficiency,storage efficiency and energy consumption of the cold storage system under the three different driving modes were simulated and analyzed throughout the year.The results show that the minimum temperature in the cold storage system can reach-4 ℃,-4.5 ℃ and-4.5 ℃ respectively,and the temperature can be stabilized at 0 ℃～5 ℃ in the stable operation stage.The annual power consumption of the three modes is 966 k Wh,916 k Wh and 440 k Wh,and the highest system COP of the three modes can reach 1.82,1.74 and 1.69,respectively.the annual storage capacity of mode 2 and mode 3 reaches 4080 MJ and 3802 MJ,respectively.(3)The experimental test platform of PV direct drive "cold storage" system was built to investigate the temperature change inside the cold storage under the direct drive of PV,and the results showed that.With the change of light conditions and outdoor temperature,the temperature in the two measurement points of the cold storage reached a minimum of-5.7 ℃and-1.6 ℃ respectively,and the temperature could be maintained between-5 ℃ and 0 ℃during the whole experiment.(4)The proposed photovoltaic energy storage type cold storage was accounted for the whole life cycle carbon emission,and a carbon emission calculation model was built for each stage of the whole life cycle of the cold storage,and the required carbon emission factors were selected from domestic and foreign carbon emission factor databases according to the carbon emission sources in each stage.The results show that the carbon emissions of building construction stage,building demolition stage,building operation stage and building materials production and transportation stage reach 1.98 t CO2,3.95 t CO2,14.3 t CO2 and 39.503 t CO2 respectively,and the production and transportation of building materials and building operation stage are the main sources of carbon emissions,and the carbon emissions of these two stages account for 88.4 %.The proposed photovoltaic energy storage cold storage system reduces the carbon emission in the operation phase by 55% compared with the traditional cold storage system. |
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