A New Type Of Combined Cooling,heating And Power System Combined With Cascade Utilization Of LNG Cold Energy And Its Application In Cold Storage

Faced with issues such as energy consumption supply and energy structure transformation,my country’s energy consumption structure still needs to be continuously optimized,and strategic measures such as the comprehensive utilization of renewable energy and the improvement of energy efficiency will continue to actively respond to new challenges in the energy transition.Distributed energy system is a new energy utilization method that uses small decentralized equipment to provide multiple energy needs close to the user end(demand side).Its "multi-energy complementary" feature can adapt multiple energy sources through complementary applications to alleviate energy.Contradiction between supply and demand.As a clean energy commonly used in cogeneration systems,natural gas produces only half of the carbon dioxide of coal and 75%of oil after combustion,which causes far less damage to the global environment than the latter two.This paper first established a solar radiation model that can be calculated according to the latitude,longitude and surface temperature of different regions,and a low-temperature Rankine cycle model that can derive the heat exchange area required for the heat exchange process of specific equipment.According to the calculation model of solar radiation,and with reference to relevant meteorological parameters,a reference map of the numerical change of the annual average solar radiation of a certain area and the annual trend is obtained.At the same time,according to the low-temperature Rankine cycle calculation model,according to certain organic working fluid selection principles,the influence of different organic working fluids on the energy efficiency of the power generation system after entering the cycle is analyzed,and the best choice of organic working fluid is obtained when considering the energy efficiency of the system.Excellent solution.Secondly,this paper studies in detail how to combine the cascade utilization of LNG cold energy with the distributed energy system to meet the load demand of the user side for the cooling capacity.The cascade utilization of LNG cold energy is specifically divided into four levels,based on its temperature changes.,Applying these four levels to air separation,production of dry ice,meeting the cold load of cold storage,and condensation demand of distributed energy systems,further reducing the energy consumption of the entire energy system.At the same time,the relevant physical property parameters of liquefied natural gas are obtained using the relevant parameter calculation empirical formula,and the calculation of the relevant physical property parameters lays the foundation for the research of the specific heat exchange process of LNG.On this basis,a calculation model was established for the specific heat exchange process of LNG in the single-phase zone and the two-phase boiling zone,and the temperature changes of the fluid inside and outside the heat exchange tube at each stage of LNG cold energy utilization were obtained.The results show that the temperature rise trend of the LNG fluid in the single-phase zone is steep and the temperature difference changes greatly;while in the two-phase boiling zone,the temperature of the LNG fluid is basically unchanged.And by changing the form of working pressure,the temperature of the LNG fluid can reach the most suitable step utilization pointIn this paper,by deriving the calculation formulas between the thermal physical parameters of lithium bromide and its temperature,concentration,etc.,the mathematical model for calculating the refrigeration cycle of the double-effect lithium bromide refrigeration subsystem is further established,and the relevant parameters of the main equipment in the cycle are obtained.On this basis,according to the physical parameter equation of lithium bromide solution and the dynamic model of ultrasonic action on cavitation bubbles in a homogeneous liquid,the ultrasonic cavitation bubble motion equation of lithium bromide solution is deduced,and the changes of ultrasonic parameters and solution physical parameters are studied.Influence on the change characteristics of cavitation bubbles in lithium bromide solution.The research results show that with the decrease of the initial bubble radius and ultrasonic frequency,the ultrasonic cavitation effect gradually increases,which provides a basis for using ultrasonic cavitation effect to enhance the heat transfer performance of lithium bromide solution and improve the performance of the lithium bromide absorption refrigeration system.In addition,according to the design scale of the cold storage and the meteorological parameters of the location of the cold storage,this paper calculates the cold consumption of various types of cold storage rooms and cold storage rooms.The cold consumption in the freezer room is basically about 3 to 4 times that of the cold room.Then synthesize the established subsystem model,give corresponding selection research and economic analysis for the specific design of the entire distributed combined cooling,heating and power system.According to the calculated results of the main equipment design,it is obtained The corresponding model equipment selection and the establishment of a thermal economic analysis model can obtain the corresponding power generation cost,investment recovery period,and environmental protection benefit analysis.