Research Of Armored Soldier Personal Cooling Systems Based On Thermoelectric Refrigeration

Armored forces are indispensable of all national military.They play an important role in modern warfare especially for their combat effectiveness and military status.Armored soldiers are the key factors for whether or not armored forces can fully exert their combat effectiveness.However,the operating environment and conditions are seriously effecting and restricting their combat effectiveness.Also,these issues threaten their health.First of all,the space inside the armored vehicle compartment is very small.Soldiers may need to operate in a windowless narrow space for a long time.Such a local environment cannot meet their normal physiological needs.Second,unusual high temperatures often occur inside armored vehicles.In hot areas and seasons,armored vehicles will absorb a large amount of external heat,such as solar radiation,during outdoor combat or training.In addition,the devices in vehicle also generate heat to the ambient.And because of the confined environment in armored vehicle compartments,heat cannot be delivered outside in time,which results in long-term sustained high temperatures in the cabins.Finally,researches on the cooling protection systems and thermal comfort of our military armored soldiers are still far from adequate.There is no complete solution to the damage caused by the high temperatures in the cabin.Therefore,it is necessary to develop cooling protection systems that are suitable for the armored forces of our army.And there is important practical significance for improving the combat effectiveness of our armored combat units.Some studies were carried out for the system design and performances of personal cooling protection systems.The main contents and results of this research include:(1)The current research status and latest developments on the armored cooling protection systems of armored soldiers were analyzed.Then the basic technical route for the study was determined and a research program was proposed.A great deal of contrasting work was done to compare the advantages and disadvantages of various existing technical routes and research programs.Individual microenvironment cooling schemes are then considered to be very viable,and liquid cooling garments are focused because of their highest cooling efficiency,comfort and safety.At last,thermoelectric refrigeration technology was identified to use as cold sources which provide cooling capacity for the liquid cooling garments.(2)The test method of steady performance for thermoelectric refrigeration devices was designed;meanwhile,a test system under actual conditions was developed.And the performance test experimental table was set up.There are many factors that can affect the performance of an actual thermoelectric refrigeration system.At the level of semiconductor couples,the relative factors include figure of merit and the ratio of area to length of galvanic couples;at the level of thermoelectric modules,there are influencing factors for the number of stages,contact resistance,thermal resistance,and the temperature difference between the hot side and cold side;as to thermoelectric refrigeration systems,there are input power,heat transfer method and conditions,and system control schemes,and so on.At present,there is no systematic method or device that can effectively and comprehensively test the above influencing factors.To meet the test requirements for thermoelectric refrigeration performance under actual conditions,effective test method and test systems have been developed,and an experimental table of the test and experiment system has been built.These works provide the basis for the design and detection of the following thermoelectric refrigeration systems.(3)A systemic individual cooling protection system was developed,prototypes were made and system performance tests were performed.A systemic individual cooling protection system was designed and developed for the highly active and heat-dissipating armored soldiers.The system is mainly composed of a cold source device and a full-body liquid cooling garment.The main research contents include:determining the system design requirements,accounting system design parameters,the designation and integration of cold source devices,selection of the liquid-cooled garment,research of heat dissipation structure of thermoelectric refrigeration components,development of the prototype system,performance testing of the prototype,etc.In the research of heat dissipation structure of thermoelectric refrigeration components,experiments of heat dissipation effects were conducted to compare the heat dissipation performance of forced convection of finned exchangers,forced convection of heat pipes,and water cooling exchangers.When the prototype of the systemic cooling protection system is manufactured,the heat-dissipation method for forced convection of the heat pipe is adopted to ensure the reliability and stability of the prototype performance.Finally,the performance test of the systemic individual cooling protection system prototype shows that the cooling power can meet the design requirements of 300W under maximum load conditions and 150W under extreme high temperature conditions.And the performance of prototype would be influenced by ambient temperature,input conditions,and circulating water flow rate.(4)A split type individual cooling protection system was developed,including thermoelectric cooling helmet system and thermoelectric cooling vest system.Prototypes of these systems were produced and tested for performance.A split type individual cooling protection system was designed and developed for the armored soldiers with requirements of high flexibility and low heat dissipation.The system is composed of a thermoelectric refrigeration helmet system and a vest system.The main research contents include:determination of design parameters,calculation of cooling capacity of each module,structural design of devices,development and integration of prototypes,performance testing of prototypes,etc.The thermoelectric refrigeration helmet can wrap the wearer's head and neck,using an air-cooled refrigeration module and a water-cooled refrigeration module.The air-cooled refrigeration module can provide cool air to the wearer's face and the water-cooled refrigeration module can provide cold water to the wearer's neck.The performance test of the split type individual cooling protection system shows that the cooling power of the two prototypes can meet the design requirements for maximum load conditions and extreme high temperature conditions.The cooling performance of the system is affected by factors such as ambient temperature,input conditions,and circulating water flow rate.And the refrigeration performance of the thermoelectric refrigeration vest is also affected by the vertical placement of the thermoelectric cooling module.(5)The wearing effect of the developed individual cooling device was evaluated by the human body's objective physiological parameters and subjective feeling evaluation methods.Physiological parameters and subjective feelings tests were performed at the same time.Five testers performed a total of 15 physiological parameter tests in a laboratory that simulates high-temperature environmental conditions in armored vehicles.Testers wearied different individual cooling protection devices and perform specific mental and physical activities within 120 minutes.The tester's physiological indicators such as body surface temperature,sweat amount,and heart rate were monitored and compared with those without the cooling device.In this way,the objective cooling effect of the cooling protection device was evaluated.Among them,10 subjects also conducted subjective comfort feeling surveys.The testers filled out questionnaires to express the subjective feelings of the experimenter's thermal comfort,thus the human thermal comfort effect of the cooling protection device was evaluated and important suggestions about system improvement were obtained.(6)Some problems were discovered during the performance testing of individual cooling devices by thermoelectric refrigeration.And the basis for important improvements was obtained.For example,the micro circulating water pump used in the water cooling module generates vibrations and noises continuously behind the wearer's head,which seriously affects the comfort feeling of the wearer and causes the wearer losing his concentration.In order to solve the problems of vibration and noise thoroughly,the feasibility of natural convection heat exchange of nanofluids instead of forced convection heat transfer of water pumps was studied.An experiment was designed to research the natural convection circulation flow and heat transfer characteristics of nanofluids;and the experimental results provided a reference for the application of nanofluids in human body cooling devices.In the research of heat dissipation structure of thermoelectric refrigeration components,a micro-nano-scale porous surface and a foamed metal-based micro-nano-scale porous surface were manufactured by electroplating.The two structures were separately fabricated on the hot end of thermoelectric modules,and two new types of phase change heat dissipating surface structures were formed.Then,experiments on heat dissipation effects were conducted to compare the heat dissipation performance of the two types of surface structures with forced convection of finned exchangers,forced convection of heat pipes,and water cooling exchangers.The experimental results show that the two types of micro-nano-scale porous surfaces have an effective boiling heat exchange interval,the cooling power and refrigeration coefficient of the thermoelectric cooling module are significantly better than the other heat dissipation methods in the interval.However,there are still some design flaws in the structure and working fluids of phase-change heat exchangers,resulting in the situation that all liquids evaporated when the thermoelectric refrigeration system operated at high power.So micro-nano-scale porous surfaces cannot be used temporarily,and further research should be focused on for improvement.The research results show that the individual cooling system developed in this paper can meet the practical needs of armored soldiers.The system provides a new technical method and related device to solve the heat stress and thermal damage problems for armored forces of our military.It also provides a reference for the development of human cooling technology based on thermoelectric refrigeration.