EduBeacon

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EXPERIMENT NO.3 OBJECT: To calculate the value of heat transfer coefficient from the fin and to determine efficiency, effectiveness of pin-fin in Forced Convection. INTRODUCTION: Extended surfaces of fins are used to increase the heat transfer rate from a surface to a fluid wherever it is not possible to increase the value of the surface heat transfer coefficient or the temperature difference between the surface and the fluid. Circumferential fins around the cylinder of a motor cycle engine and fins attached to condenser tubes of a refrigerator are a few familiar examples. It is obvious that a fin surface sticks out from the primary heat transfer surface. The temperature difference with surrounding fluid will steadily diminish as one move out along the fin. The design of the fins therefore required knowledge of the temperature distribution in the fin. The main objective of this experimental set up is to study temperature distribution in a simple pin fin. APPARATUS: A b

EXPERIMENT NO.2 OBJECT  To calculate the value of heat transfer coefficient from the fin and to determine efficiency, effectiveness of pin-fin in Natural Convection. INTRODUCTION  Extended surfaces of fins are used to increase the heat transfer rate from a surface to a fluid wherever it is not possible to increase the value of the surface heat transfer coefficient or the temperature difference between the surface and the fluid. Circumferential fins around the cylinder of a motor cycle engine and fins attached to condenser tubes of a refrigerator are a few familiar examples. It is obvious that a fin surface sticks out from the primary heat transfer surface. The temperature difference with surrounding fluid will steadily diminish as one move out along the fin. The design of the fins therefore required knowledge of the temperature distribution in the fin. The main objective of this experimental set up is to study temperature distribution in a simple pin fin. APPARATUS

                                                   EXPERIMENT NO. 1 OBJECT:- Conductive thermal resistance of the given system. Thermal conductivity of a given insulating powder. Critical thickness of insulation. APPARATUS:- The apparatus consists of two thin walled concentric copper spheres. The inner sphere houses the heating coil. The insulating powder (Asbestos powder) is packed between the two shells. The power supply to the heating coil is by using a dimmer stat and is measured by Voltmeter and Ammeter. Thermo-couples are use to measure the temperatures. Thermocouples 1 to 6 are embedded on inner sphere and 7 to 12 are on outer sphere. Temperature readings enable to find out the Thermal Conductivity of the insulating powder as an isotropic material. FORMULAS:- For the prescribed spherical geometry shown in diagram: Heat input can be expressed as - Thermal Resistance  Using equation (1) & (2) Where,   Radius of inner sphere r i = 50 mm =

Space borne Cooling Systems Some spacecraft payloads require cooling to low temperatures. The most common types of cooled instruments include IR-sensor focal planes and optics, as well as Low-noise amplifiers for RF receivers. Several devices are available for cooling such applications, including radiators, stored-cryogen cooling systems, and refrigerators. The Defense Support Program (DSP)satellite uses a system of radiators to cool the optics and focal plane. Parts in DSP sensor – Thermoelectric coolers Helium circulators Phase Change Materials (PCM) canisters Forward facing radiators (FFR) TCS electronics unit and power supply Concept - Helium circulator transports focal plane/PCM heat to nonsolar illuminated forward-facing radiator (FFR) Circulator turned off when FFR solar illuminated-focal plane heat melts PCM PCM is refrozen when circulator resumed refrozen when circulator resumed Working:- The optical elements (mirrors) and the telescope e