Study On The Warming Performance,Cooling Performance And Hot Air Defrosting Of Central Air Supply Cold Storage

Central air supply cold storage is a trend in the development of cold storage industry in recent years,due to its advantage of central supply,much cooling capacity is provided.Because of its high efficiency,low energy consumption and economy etc advantages,which is of great practical value of engineering application,has the vital significance to the development of refrigeration industry,the researchers in the related research institute and universities carrying out a large amount of experimental study.The central supply air refrigerator test of this experiment used is divided into 10 cold storages as a whole,the material of cold storage palisade structure is polyurethane rigid plastic.And the air cooler is in a relatively closed space which is outside the cold storage.Through the thermal insulation layer,using the central air supply system to supply air to the each cold storage through pipe.Based on the central supply air refrigerator test,the experiment of cold storage palisade structure heat transfer,cold storage cooling performance,warming performance,air cooler frosting and hot air defrosting experiment,and the related theoretical analysis model is established.Through the combination of experiment and theoretical analysis,the study of the centralized supply air refrigerator performance was carried out.With the experimental and theoretical analysis of the quantity of heat transfer of the building envelope in the experiment,the value of the quantity of heat transfer of the building envelope presents a trend of increasing when the temperature of the cold storage is lowing down.And the results of the experiment indicates that the theoretical value and the experimental value is relatively close,which proves the practical usefulness of the theoretical value.In the experiments of cold storage cooling and warming performance,the performance of cold storage cooling performance experiment was firstly carried out.In the experiment,each cold storage of supply and return wind valves were turned on at the same time,the purpose was to low down the temperature of each cold storage cooling at the same time,neglecting the influence of the pipeline pressure difference,assuming the air flow of each cold storage is the same,the change of each cold storage temperature is the same over time.The experimental and theoretical analysis shows that with the reduction of cold storage temperature,cooling rate significantly decreased,and cooling time increases significantly.When the temperature of cold storage decreased from 10 ? to-20 ?,the time used is about 9.7 hours.In the cold storage warming performance experiment,the refrigeration system,each cold storage of supply and return wind valve was shut off to form a relatively closed space and then the cold storages got heated up in a natural state.The experimentaland theoretical analysis shows that under the high cold storage temperature state,the time spent on cold storage warming is relative short,under the low cold storage temperature state,the time used for cold storage warming is longer.When the temperature of cold storage warm from-20 ? to 10 ?,the time used is about 13 hours.Through to the experimental and theoretical analysis of the refrigeration system operating air cooler frosting shows that with continuous operation of the refrigeration system,the air cooler frosting quantity presents the increasing trend,when the temperature of cold storage is-20 ?,the frosting quantity reached 3.52 ?.In the hot air defrosting experiment,firstly,the electric heater was used to heat the air,after reaching a certain temperature,control the temperature,and then pass into the air cooler for defrosting experiment.Through experimental and theoretical analysis,it shows that with the reduction of cold storage temperature,frosting quantity increase,and the time that defrosting took became longer.Under the condition of the same frosting quantity,the time that defrosting took showing a decreasing trend with the increase of hot air temperature,when the temperature of cold storage is-20 ?,the hot air temperature is20?,the time of defrosting is 3670 s,the hot air temperature is 40 ?,the time of defrosting is 2495 s.