ISSN:0145-7632    

DOI:10.1080/01457639608939881

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A method for unsteady, axisymmetric, conjugate heat transfer analysis has been developed. The conjugate heat transfer domain comprises co-flowing high-temperature air and subcooled water coolant on opposite sides of a copper-zirconium, converging nozzle. Heat transfer through the nozzle wall is characterized by solid-body conduction with convection boundary conditions along the air side and water side of the nozzle wall. The air-side heat transfer is characterized by forced convection with a turbulent boundary layer. The water-side heat transfer is characterized by forced-convection, subcooled, nucleate boiling. Convective heat transfer coefficients on each side of the nozzle wall are functions of the wall temperature and the respective flow properties, thus coupling the three regions of the domain. The solution method marches in time, solving, at each time step for the nozzle wall temperature distribution, the flow properties on each side of the nozzle wall, and for the convective heat transfer coefficients. The algorithm terminates when either the steady state is achieved or nozzle wall failure conditions are reached. Solutions are obtained for four test cases culled from the run history of the Arnold Engineering Development Center HEAT-H1 Test Unit. Results show that the recorded test case failures were not caused by precritical boiling effects. Conclusive failure analysis for the HEAT-H1 test cases awaits application of an appropriate convective boiling critical heat flux model, along with creep and stress-rupture models for the nozzle wall.

ISSN:0145-7632    

DOI:10.1080/01457639608939882

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Reciprocating heat pipes are novel heat pipes that are being developed for engine piston applications. These heat pipes have a high effective thermal conductance due to the impinging effects of liquid particles in the heat pipe. In this investigation, semiempirical correlations for the dimensionless temperature distribution and effective thermal conductivity of heat pipes are derived. Extensive experiments are conducted to investigate the effects of thermal and geometrical conditions on the performance of reciprocating heat pipes, and a large number of experimental data are generated. Experimental results indicate that the effective thermal conductance of the reciprocating heat pipe can be more than 300 times that of a solid copper bar of equal size. Comparison of the experimental data and correlation shows that the experimental data can be correlated to within ±30% by the correlation derived, which provides a quantitative relation for heat pipe design purposes.

ISSN:0145-7632    

DOI:10.1080/01457639608939883

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Heat transfer to electrolyte solutions is a common engineering problem in the chemical and petrochemical industries. Nevertheless, only a few experimental investigations of heat transfer to electrolyte solutions can be found in the literature. To improve design of heat transfer equipment and to understand fouling characteristics, it is important to know the clean heat transfer coefficient of electrolyte solutions, and whether heat transfer to electrolyte solutions can be predicted with models found for less complicated fluids. A wide range of experiments were performed to determine the effects of various dissolved salts on forced-convective, pool boiling, and subcooled flow-boiling heat transfer. The effect of dissolved salts on bubble size and nucleation site density were also investigated. The measured heat transfer coefficients are compared with recommended correlations for the different heat transfer modes.

ISSN:0145-7632    

DOI:10.1080/01457639608939884

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

An experimental investigation was carried out to determine the thermal performance of a heat exchanger operating with vertical upflow of a hot gas loaded with solid particles. Using particles having mean diameters (88-157 μm), the inlet gas velocity was varied from 1.5 to 13 m/s and the inlet temperature was varied from 100 to 600°C. This resulted in mixture densities of 2.0 to 30 kg/m3for the gas-solid flow.

ISSN:0145-7632    

DOI:10.1080/01457639608936948

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

This study has found that liquid film breakdown in isopropanol, ethylene glycol, and water mixtures occurred only in systems with negative surface tension gradients. These systems were characterized by a decrease in local surface tension with a decrease in film thickness. Thus, the direction of surface tension gradient with respect to film thickness can be used as a criterion for predicting falling film breakdown in certain mixture systems.

ISSN:0145-7632    

DOI:10.1080/01457639608939885

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor