共查询到20条相似文献，搜索用时 609 毫秒
1.
The advantages of spray dry scrubbing of MSW incinerationflue gas include simple system, lowinvestment and operating costs, byproductwithout waste water and so on. Spray dry scrubbingis a very promising technique. Heat transfer, mass transfer and chemical reactionbetween alkaline dropletand flue gas in the spray dryer areanalyzed in detail. Calculation formulas of heat transfer and mass transfer of four-step of dropletdrying are gained. Influence factors of spray dry scrubbing acidgas componentsare also analyzed. The conclusionlay the foundation for establishing mathematicsmodel of spray dry scrubbingprocess. 相似文献
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In recent years, sewage source spray heat exchanger was widely used in sewage source heat pump systems with its higher heat transfer coefficient, easier operation and maintenance and less energy, etc. In this paper, we studied the direction arrangement of heat exchange tubes of spray heat exchanger. And the heat transfer coefficient, film coverage, effective area ratio has been studied through mathematical tools and CFD simulations and other means. The results showed that in the sewage-source heat pump project, when the engine room area is relatively small but highly space is sufficient, the vertical arrangement of spray heat exchanger tubes can obtain a good effect. 相似文献
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In order to study the cooling characteristics of the nozzle, a test platform is designed and developed for spray cooling feature measurement based on unsteady state heat conduction. By heating and keeping Q215 metal samples up to some surface temperature, a series of temperature data are collected by S7-200 modules during spray force cooling. Through Visual C++6.0 and Matlab interface programming, a series of regression equation with thermodynamic property versus temperature, such as density, specific heat capacity, and thermal conductivity etc., and with temperature versus sample time are obtained. The surface heat transfer coefficient and spray cooling feature of nozzle can be indirectly measured by the regression equations. The relation between surface heat transfer coefficient versus temperature, spray pressure and water intensity are investigated by means of the testing equipment. The experiment result shows the method is feasible and can be used in spray cooling feature measurement for all kinds of nozzle. 相似文献
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地埋管地源热泵换热器的换热性能受到不同地质结构的影响。以武汉和重庆地区的典型地质构成为边界条件，建立了三维地埋管的单孔双U管换热模型，通过模型计算，获得了两种地质条件下的地埋管换热性能，以重庆地区的地源热泵热响应测试结果以及工程运行数据出发，对模型的计算结果进行了验证，结果表明，模型吻合度较好，可以应用于工程分析。以模型为条件，进行地质结构对换热性能的影响度分析，预测了两地地埋管地源热泵的换热性能并计算得到换热器的平均换热系数分别为武汉地区K1=1.65（W/m·K），重庆地区K2=1.51（W/m·K）。 相似文献
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Rectangle fin is widely used in different kinds of heat exchangrs. Convection heat transfercoefficient distribution over the fin surface is one of the theorehcal problems in research on enhancement of heat transfer. In this paper, a tube with an attached rectangular fin is used for a model and thefin surface is divided into a network of nodes by the finite difference techinque. When the wind velocityis u= 4. 5 m/s. the temperature distribution of discretization is obtained by experimental measurement,then the convection heat transfer coefficient of all nodes are soved by using the methed of inverse heatconduction problem. Through checking with heat balance methed, the results show that the solution cancorrectly express the actual heat transfer situation.This result is useful to experimental research onenhancement of heat transfer for finned for heat exchangers. 相似文献
7.
Based on the first and the second laws of thermodynamic, the entropy generation of heat transfer process from the inside to the outside through a duct is analyzed. A dimensionless entropy generation number based on the fluid of inside duct is introduced and an analytical expression for the dimensionless entropy generation number is obtained. The effect of some dimensionless parameters on the irreversibility performance of heat transfer process through a duct is discussed. The results show that an optimal Reynolds number of fluid inside duct is found to make dimensionless entropy generation number minimum , the dimensionless entropy generation number increases with the increment of the ratio of the Reynolds number of inside and outside duct fluids, dimensionless inlet temperature difference and dimensionless characteristic geometric dimension. The results from this paper provide a reference for the thermodynamic performance evaluation on the basic heat transfer process through a duct and enhancement in double sides of duct. 相似文献
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In this paper, experimental results on heat transfer performance of a low integral-fin tube, thermoexcel-C tube (C tube) and a new horizontal double-side enhanced condenser tube (GC tube) have been reported for condensation of R-11. Within our experimental scope,the overall heat transfer coefficient of the GC tube can increase more than 5 times that of the smooth tube . And the relevant friction factor inside the GC tube can be 7 times that of the smooth tube. The Second law of thermodynamics was applied to develop a new criterion to assess the heat transfer performance of the GC tube,the C tube,the low integral-fin tube,and the DAC tube[1] (another doubleside enhanced condenser tube). The result shows the heat transfer performance of the GC tube is superior to the other tubes from a thermodynamical viewpoint. 相似文献
9.
Serpentine radiant heat transfer pipes(SRHTP)are expensive and with low heat exchanged, so the heat transfer panel with capillary imbibition core (HTPCIC) is put forward. HTPCIC is composed by potassium citrate-plaster (PCP), and PCP board becomes a uniform channel of which the flow rate is 55.3% when water is cooling medium. By changing the emissivity of HTPCIC' surface(low emissivity 0.23,high emissivity 0.95)and the temperature of cold-water(7~18 ℃), at 26 ℃ (±1 ℃), heat transfer characteristics of HTPCIC are analyzed whose average pore radius is 0.015 mm and porosity is 55.3%. The experimental results show that the cooling capacity of HTPCIC meets the requirements of conventional radiation air-conditioning, and compared with SRHTP, the initial cost reduces by 80%. Moreover, regression equation of the HTPCIC heat transfer guideline is proposed: Nu=0.029Re0.21Pr2.6θ0, which provides basis for establishing a complete design theory. 相似文献
10.
Wu Chengbo 《保鲜与加工》1998,(1):88-94
By the calculation and experiment,analysed the heat transfer characteristies in waste gas of the high temperature exchanger.The results which the reasonable vertical and horizontal distances were obtained,these turned out that the metallic rediation net was the effectve method intensified heat transfer in hot waste gas.The infulence of the velcity and temperature of waste gas on the multiple heat transfer caefficrent of the exchanger was studied by the experiment data. 相似文献
11.
Kang Gewen Liu Fei Xu Zongjun Tong Qinmin 《保鲜与加工》1997,(1):43-49
The models for dynamic heat transfer of chips and tools are developed based on analysing heat source distributions in orthogonal dry cutting process,and a procedure is proposed to compute the temperature distributions of chips and tools,and the heat partition coefficients between the tools and the chips. 相似文献
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Using ammonia as coolant, experiments are performed to investigate heat transfer characteristics and surface temperature distribution for the spray cooling of 350 W/cm2 high power solid state laser. When the heating power and spray height were constant, the cooling surface was mainly dominated by forced convective heat transfer, high inlet flow rate of liquid ammonia resulted in low surface temperature and uniform temperature distribution. When the volumetric flow was 0.461 L/min, the cooling surface temperature was only 2.6 ℃ and the temperature deviation was ±1.1 ℃, the heat flux dissipated could reach 388 W/cm2. As the inlet volumetric flow decreased, the dominant heat transfer mechanism for spray cooling gradually converted the forced convective heat transfer to the boiling while increasing heat flux, resulting in decrease of uniform temperature distribution of heat transfer surface. 相似文献
14.
High thermal resistance resulted by fouling in heat exchanger restricts the application of sewage source heat pump (SSHP) system. The fouling forming mechanism was applied with solid-liquid fluidized bed technique for fouling prevention and removing of SSHP system. Shearing stress model of solid-liquid fluidized bed heat-exchanger is analyzed, and collision stress model is modified. Preventing and removing fouling mechanisms of solid-liquid fluidized bed technique by shearing stress and collision stress was explained. An experimental study on how to solve the fouling problem (such as fouling prevention and removing, heat transfer enhancement, etc) is discussed. The results of theory and experiment show that solid-liquid fluidized bed technique can be used not only to increase convection coefficient, but also to restrict fouling growing, it can effectively solve the fouling problem in SSHP system. 相似文献
15.
Soil temperature prediction model around the subway metro tunnels is constructed with the consideration of coupled heat transfer between range temperature and surrounding soil. Finite difference method is adopted for numerical solution of the model, and the solving results in certain conditions are compared to validate the analytical solution. The high-frequency thermal disturbance brought by train operation is simplified into three different forms, and the predictive model of soil temperature is used to calculate the corresponding soil temperature response. It is indicated that temperature fluctuations of range air and the wall are accompanied with high-frequency thermal disturbance, but the impact on soil temperature distribution inside is limited. 相似文献
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The heat transfer process in the louvered fin heat exchanger is analyzed,and the corresponding physical and mathematical models on the coupled conduction-convective heat transfer for the louver fin geometry are proposed.The control volume-based finite element method(CVFEM) is employed to solve numerically the problem.The computed(results) reveal the flow structure and heat transfer in the geometry in detail.Compared with the empirical correlation of heat transfer and friction coefficients previously proposed,the computed results show better consistency with the experimental results. 相似文献
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In this paper,the comparative experimental research that air flows through theout-surface of a single row finned tubes is done in a drawing wind tunnel and the three differnetshapes of rectangluar finned tubes are compared with a plain finned tube that is usually used in therefrigerant heat exchanger, the useful results are obtained. The results show that,in the range ofwind velocity flowing through the marrowest area, W_(max)=2.5m/s to 8.5m/s,the average convec-tion heat transfer coefficient of the two-side V-groove finned tube is higher than that of rectangluarplain finned tube,It is a new type finned tube that has good heat transfer performance and it isworth poplarlzing. 相似文献
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The experimental study of the flow resistance and heat transfer characteristics are conducted for water and ethylene glycol solution (66% Wt) flowing in the heat exchanger with small rectangular microchannels . The heat exchanger having the channels of 0.4 mm in width, 2.0 mm in height, and 20 mm in length is heated by a hearing rod at the bottom surface, the upper and two side surfaces are adiabatic. During experiments, the Reynolds number are ranged from 2 to 2 500. The experimental results show that the flow friction factor decreases and Nusselt number increases with increasing Reynolds number for water and ethylene glycol solution. At a fixed Reynolds number, the Nusselt number for ethylene glycol solution with larger Prandtl number is greater than that for water. Meanwhile, the correlations of flow resistance and heat transfer in the heat exchanger with small channels are obtained for engineering application. 相似文献
19.
The paper uses CFD simulation to investigate the catalytic surface reaction and heat loss characteristics of premixed CH4/air in micro-channels with Platinum catalyst. A 3D model is used with the detailed surface elementary reaction mechanism, which includes the coupled heat transfer of wall and flow domain, solid wall thermal conductivity and the convection and surface radiation between wall and the environment. The results show that the thermal conductivity has a big impact on the uniformity of wall temperature. The convective heat transfer coefficients and the surface emissivity are the key factors to determine the external heat loss of micro-combustor. An increase of wall depth can reduce the external heat loss per unit area, but it increases the total heat loss. The change of the amount of heat loss changes the reaction rate and residence time of mixed gas in the channel, which affect the methane conversion. The research indicates that the material with bigger thermal conductivity is better to fabricate micro-combustors, and the multi-methods are needed to reduce the wall heat loss. 相似文献