Optimization of MCHX Using CFD and Refrigeration Cycle Simulator

Micro channel heat exchangers (MCHX) can be broadly classified as fluidic devices that employ channels of hydraulic diameter smaller than 1 mm. The present study focused on validate the better configuration parameters of louver fin used in MCHX for apply in residential air-conditioner condenser. The study has considered for three different louver angle case, two different louver lengths for better louver angle case and finally two different louver pitches for better louver angle and louver length case. The study indicates that the pressure drop will depends upon the louver angle and pitch. The louver angle i.e. 25deg provides reasonable pressure drop and high heat transfer rate. Thus by changing the length of louver can increase the pressure drop in MCHX. The case ie., 1.2mm louver length have more heat transfer rate. But when comparing to 1mm louver length case Net Heat Transfer rate is high. So the study further continued by having the louver length 1mm and changing the louver pitch. The louver pitch 0.8 and 1.2 has only considered for the study. The length of louver can decrease the pressure drop in MCHX. The variation of net heat transfer rate to changing the louver pitch indicating the importance of number of louver present in the MCHX. Thus the present study indicates the importance of configuration parameters for MCHX. The study also indicates that the increasing the louver length and angle will increase the net heat transfer rate. While increasing the louver pitch is inversely proportional to the net heat transfer rate of MCHX.

Round Bar Heating With Swirl Burners

A method of heating round steel bars using a swirl burner or swirl burner furnace combination is described. This technique is suitable for surface hardening or processing of long steel bars. The uniform heating around the steel bar, coupled with the high heat transfer rate of the swirling flow, allows a relatively small swirl burner to be used. Experimental results are presented from small-scale prototype trials with a 200 kW burner and 25 mm diameter mild steel bars.

Heat Transfer and Friction Loss Characteristics of Pin Fin Cooling Configurations

Pin fin or full cross pin cooling configurations have long been of interest to the turbine cooling designer because of their potentially high heat transfer characteristics and high surface area density, as well as their structural and castability advantages. The pin fin cooling configurations consist of flow channels with circular pins extending from the walls into the channel flow. The pin fins function as turbulators to produce high heat transfer rate; however, their geometric arrangement must be optimized to avoid high friction loss. Experimental tests have been conducted to investigate the effects of pin heights, spacings, and channel height to length ratios to the heat transfer and friction loss characteristics of the pin fin cooling configurations. The test results indicate that the pin fin configuration provides a means to reduce the flow friction loss and yet to maintain a reasonably high heat transfer rate as compared to the cross pin configuration. The pin spacing in the test range shows less effects on the pin fin performance than the pin height.