Thermal Characteristics And Temperature Control Of Power-generation Cabin In Antarctic

Dome A lies at the highest point of the Antarctic plateau.Its altitude is about 4100m and the annual mean temperature is about-60?.The ambient temperature there fluctuates obviously throughout the year.The development of reliable and efficient support platforms is a prerequisite and primary security concern for carrying out astronomical observations because of the extreme site environment.As the energy supply for the astronomical support platform,the thermal characteristics of the power-generation cabin directly determines the successful operation of the whole astronomical research platform.The power-generation cabin is an energy supply system coupled with multi-heat-source which leads to a complex heat exchange relationship within the system.The overheating or overcooling may occur in the cabin when the outside temperature fluctuates throughout the year.In addition,the power generation performance and heat balance characteristics of the diesel engine are affected by the thinness of the Antarctic air Sufficient cold air must be blown into the cabin,so the heat balance of the cabin will be significantly disturbed by the entry of the outdoor low temperature air.Therefore,how to ensure that the internal working temperature of the power station is stable and within a safe range is an important challenge faced by the development of the scientific platform,and it is also the premise and basis for studying the failure mechanism of the system.The existing thermal balance calculation of the power-generation cabin is based on the steady state extreme low temperature environment,and the research on the thermal dynamic processes throughout the year in the Antarctic extreme environment is quite scarce.Accordingly,the influence of low pressure on power generation performance and thermal balance characteristics of diesel engine are measured by low pressure environment simulation experiment.Then a thermal model of the power-generation cabin is developed on the basis of the lumped parameter method to investigate the thermal dynamic characteristics of the power-generation cabin under annual temperature variation and different strategies.Meanwhile,the state space principle and classical control theory are applied to the thermal dynamic model for the temperature control and energy management of the power-generation system.The major work and conclusions of this article are summarized as follows:First of all,the power generation performance and heat balance characteristic of diesel engine in low pressure environment are researched through the diesel engine performance testing bench.The experimental study reveals that the generation performance and the heat balance characteristics of diesel engine are overwhelmingly influenced by the Antarctic air pressure.It appears that the low pressure significantly degrades the combustion efficiency of the diesel engine in the Antarctic condition,but both the heat load and the temperature level of the whole machine increase contrarily due to the delay of combustion and the deterioration of heat dissipation.In addition,the power output,heat dissipation and exhaust loss of diesel engine gradually grow with the increase of diesel engine speed,and the growth rate turns slow under high speed condition.The ratio of heat dissipation to power of diesel engine at Antarctic pressure is higher than that under normal pressure.It is found that the diesel engine has the best speed of minimum fuel consumption at different air pressure,and the optimum speed is generally located in the medium speed range.It is noted that the difference of power generation efficiency under those two pressures is not obvious at low speed,but the power generation efficiency decreased a lot under Antarctic low pressure at high speed.Considering the economy and reliability of power generation,the recommended diesel engine speed is 2200r·min^-1 under the low atmospheric pressure in the Antarctic.And then,a thermal characteristic model of the power-generation cabin is establishedand the thermal dynamic process of a power-generation cabin under the annual temperature variation is investigated.The effects of ventilation rate and intermittent operation on the indoor air temperature are examined and analyzed.The result indicates that the temperature of the power-generation cabin exceeds the acceptable level in the case of no active air exhaust,so an exhaust fan should be configured in order to maintain the reasonable temperature in the cabin.The air temperature in the cabin can be adjusted to 0?³0?by means of variable air volume strategy when the diesel generator runs normally.It's necessary to utilize the electric heater during the shutdown of the diesel generating due to the air temperature and the bottom fuel temperature in the cabin decrease obviously.The thermal inertia of different components are distinctly different from each other during the starting process of diesel generating set,resulting in a huge temperature difference between the bottom fuel and the indoor air as time goes on.Therefore the temperature uniform measure should be conducted to avoid the freezing of the bottom fuel.At last,an temperature uniform measure has been proposed to optimize the heat transfer structure of the power-generation cabin.A heat control model is developed to strengthen temperature control and energy management of the power-generation cabin according to the control theory.The result shows that the temperature of indoor air and the bottom fuel in the cabin can be stabilized at 10⁴0?and-5⁵?respectively.And the temperature gradient between the upper and lower parts of the power-generation cabin can be effectively reduced.The indoor air temperature is seriously affected by the external temperature disturbance while the bottom fuel has greater thermal inertia for the external temperature variation.Sothe exhaust fan operates more frequently than the oil temperature control fan throughout the year.Besides,the recommended action step of the controller is 30 min while the energy consumption and temperature stability are considered synthetically.To summarise,the present work gives thermal data for the thermal characteristic investigations of the power-generation cabin in Antarctic,and it provides effective technical assistance for the development of the independent energy support control system of the Chinese Antarctic observatory.