An experimental investigation of a heat pipe integrated power module
A novel flat plat heat pipe (FPHP) integrated in high power module instead of metal substrate is developed. Compared with the metal subtrate, the FPHP uses two-phase boiling heat transfer to diffuse heat flux in power module.Thus the FPHP diffuses significantly the collect heat source to the more larger condensation area. Analyze the use of a FPHP as a heat spreader to spread out the heat from the die to the heat sink.The transient and steady heat transfer performance of the FPHP was experimentally measured.The experiment indicates that the FPHP of isothermal and high convection coefficient can improve the heat transfer capacity for the integrated power electronic module (IPEM), which make thermal resistance decrease 30 percent. The maximum thermal flux density of IGBT die is obtained to 186 W/cm2. IPEM based on FPHP can avoid the power uprush and raise the ability of resisting thermal impact.
Design and Technology of Heat Pipes for Cooling and Heat Exchange
Introduction HEAT PIPE CHARACTERISTICS The Role of Capillarity in Heat Transport Pressure and Temperature Distributions Heat Transport Limits Heat Pipe Startup References HEAT PIPE TECHNOLOGY Heat Transport Fluids Containment and Wick Materials Wick Characteristics Heat Pipe Fabrication Environmental Influences on Heat Pipe Operation Heat Pipe Systems References FLUID FLOW IN A HEAT PIPE The Nature of the Flow Process General Pressure Drop Formulation Frictional Pressure Drop for Constant Surface Mass Flux Frictional Pressure Drop for Nonconstant Surface Mass Flux Hydraulic Diameter Frictional Pressure Drop in a Porous Flow Passage Frictional Pressure Drop for Convective Cooling References HEAT TRANSPORT LIMITS Capillary Pumping Limit Sonic Limit Entrainment Limit Boiling Limit Heat Pipe Operational Boundaries Comparison of Calculated and Experimental Heat Transport Limits References HEAT PIPE DESIGN: STEADY STATE Design Criteria and Constraints Heat Pipe Area-Temperature Relations Heat Pipe Internal Dimensions Structural Considerations Additional Design Topics Heat Pipe Exchangeers References HEAT PIPE DESIGN: TRANSIENT BEHAVIOR Heat Pipe Startup Features of the Transient Model Transient Equations Calculational Procedure Assessment of Heat Pipe Startup References DESIGN EXAMPLES Heat Pipe Space Radiator Transient Analysis of the Heat Pipe Space Radiator References Appendices
Numerical and experimental investigation on air distributor design of fluidized bed reactor of sawdust pyrolysis
Abstract An improved biomass conversion in a lab-scale fluidized bed reactor (FBR) is achieved by optimizing the air distributor orifice size and number. Two approaches for introducing air were numerically and experimentally examined. These included perforated plate and downward orifice sparger. 3 mm and 5 mm orifice diameters, and 7, 9 and 13 holes were simulated at flow velocities of 2, 4, 6, and 8 times the minimum fluidization velocity, Umf. The simulation results revealed that increasing the orifice number has a positive effect on gas holdup, particularly for the perforated plate, which showed a uniform distribution of bubbles. The sparger configuration produced larger bubbles sizes, which could lead to better recirculation of solid flux, while stagnant particle zones were observed at the lower section of both distributors. A pyrolysis unit is also inserted at the top of freeboard of the FBR. For perforated plate with 6Umf, the pyrolysis process achieved thermal and cold gas efficiencies of 82.91% and 52.03%, respectively, while combustible gases with 41.6%mol CO, 8.7%mol CH 4 and 2.17%mol HC, were obtained. For sparger pipe and 6U mf _sp, 35.33 ppm NOx and 111 ppm SO 2 were measured in flue gas from combustion process at bed region.