A PROCESS OF CONFIGURATING MICROSIZED CHANNELS HAVING IMPROVED INCLINATION AND FOR ENHANCEMENT OF BOILING HEAT TRANSFER OVER PLANE SURFACE

摘要

Accordingly, there is provided a process of configurating microsized channels having improved inclination and geometry for substantial enhancement of boiling heat transfer over plane surface. The process includes Initially, surfaces with tunnels of constant width (0.25mm), constant pitch (2 mm) and constant depth (2mm) from the top surface, are developed. Variations in respect of the inclination of the tunnel including the additional geometrical feature at the tunnel base is selected. To differentiate between the different tunnel geometries, a hexa-character symbolic specification has been adapted. For example; unidirectional tunnel geometry with vertical tunnel (90° with horizontal), 2 mm pitch, 2 mm depth, 0.25 mm width and Circular base geometry is denoted by U-90-2-2-0.25-Cir. Surfaces are prepared by wire-electro discharge machining (Wire-EDM or WEDM). Micro channel fabrication operation with one machining pass is conducted using a low sparking energy by applying 70 to 100V, and a maximum current of 6 to 10A with 0.08 to 1.02 µm ON and OFF time pulse durations. Demineralized water of high insulation resistance is used as a dielectric medium. Surface is cleaned thoroughly by alkaline cleaner, acid cleaner and water mixture to remove oil or grease from it after preparation. The invention further relates to a device for determining the boiling characteristics of enhanced heat transfer surfaces. The device is configured to determine the pool boiling heat transfer from horizontal, smooth or structured surfaces. The main components of the device are a boiling vessel , a heater assembly , a reflux condenser , a top cover , power supply and instrumentation . The cylindrical boiling vessel, stores the liquid pool and forms a top part of the device. Liquid pool rests on a bakelite plate which also facilitates a horizontal test plate to be in contact with the liquid and resist the liquid to enter in the heater assembly . The horizontal test plate is a part of the heater assembly and it protrudes inside the boiling vessel . A copper plate is used as the test surface.