Research On Heat Transfer And Flow Characteristics Of Capillary Radiation Air Conditioning Technology

The radiation air conditioning has been gradually developed for its comfort, lowenergy consumption, and take advantage of the forced convection heat transfer inmicrochannel of the porous medium the has been proved to be one of the mostdevelopment potential and efficient cooling solutions. This paper propose a newdevelopment direction of air-condition combined with radiation air-conditioningtechnology and forced convection heat transfer of porous medium. In this paper, studieshas been done direct at the capillary wick radiation air-conditioning system of the heatexchanger plates, convection and radiation heat transfer, radiation air conditioningrefrigerant medium in the internal flow characteristics of the porous medium. The maincontents are as follows:The heat transfer panel of capillary imbibition core technology of this paper isderived from the heat pipe technology, which need to enough capillary pumped forceand smaller flow resistance in the capillary wick heat exchanger plates to obtain themaximum cooling capacity (heating capacity). First, the porosity of the porous medium,hydrophobic speed, the pore radius and the bearing strength of the porous medium wasstudied. The best ratio of the material was found by adding the retarder.Through comparing with the ending equipment heat exchange technology of thetraditional radiation air conditioning, the third generation heat transfer panel of capillaryimbibition core was designed on the basis of the experiment. According to buildingexperimental model space, heat exchange capacity of the heat transfer panel of capillaryimbibition core was test under the conditions of the different refrigerant inlettemperature and transmission rate, and compared with the serpentine radiation under thesame conditions, analyzes the spatial temperature distribution in different plate surfacetemperature, the experimental results show that: cooling capacity increase of37%～57.7%compared with conventional serpentine radiant tube under the conditions of thecold water inlet temperature from10℃to16℃. When increasing the surface emissivity,the spatial temperature distribution is more uniform, mainly because as the surfaceemission rate increases, an increase in the radiation heat transfer, the spatial temperaturefluctuations is smaller. The paper analyzed the continuous heat exchange process andproposed the heat exchange between the refrigerant medium and capillary wick wallsurface, the heat transfer panel of capillary imbibition core and the decorative layer, ceiling surface and the room air and radiation heat transfer in different surfaces. Get theceiling surface temperature and the integrated heat transfer coefficient calculationformula of the heat transfer panel of capillary imbibition core air conditioning system.All of these constitute the mathematical description of heat transfer between capillarywick radiation heat transfer plate and indoor space. It laid a certain theoretical basis forapplication of the heat transfer panel of capillary imbibition core.The flow resistance model of capillary wick radiation was build basis on the flowtheory of the porous medium and the Hagen-Poiseuille equation that is the function ofthe porosity, pore radius, particle diameter, fluid properties, fluid velocity and tortuousdegree. The model does not contain empirical constants and each parameter has a clearphysical significance. With comparison, the model fit well with hagen equation and theexperimental data, to prove the rationality of the model. Comparative analysis the flowresistance of the heat transfer panel of capillary imbibition core and conventionalradiation heat exchange serpentine tube, and use of the ICP-Optional EmissionSpectrometer on the circulation of water in the heat transfer panel of capillaryimbibition core running the calcium ion concentration tested.The paper analyzed energy consumption of conventional air-condition and theradiation air-condition and proposed the integrated cooling degree and centralizedcooling degree based on the first law of thermodynamics, then energy-saving reasons ofradiation air condition was revealed, that is the radiation air condition designtemperature is lower2~3℃than the design temperature of the conventional airconditioning. Then the paper analyzed the energy-saving advantages of the capillarywick radiation air conditioning basis on the second law of thermodynamics exergy valuetheory.Finally, the capillary wick radiation temperature gradient within the heat exchangerspace and internal porous medium flow pressure drop were analyzed according totheoretical analysis, C programming language and CFD numerical simulation method.The numerical results verify the reasonableness of the experiment and modelcomparison with experimental data, the model formula and the Hagen formula. Theselaid the theoretical foundation for heat transfer panel of capillary imbibition coreradiation air conditioning.