The Hilton Thermal Conductivity of Liquids and Gases Unit have been designed to enable students to easily determine this important property of a wide variety of fluids and gases. The unit will be of interest to everyone involved with heat transfer.
- Description of apparatus:
This unit consists of:
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- Pug/Jacket Assembly :Cylindrical water jacket constructed from nickel plated brass and fitted with K type thermocouple to measure inner surface temperature. Mounted on stainless steel stand. Cylindrical plug, machined from aluminum anodized. Housing heating element and K type thermocouple. Provided with ports for introduction and venting of fluid under test.
- Console:Aluminum and plastic coated steel console hosing: variable transformer; Voltmeter; Digital temperature indicator with selector switch – Resolution 0.1؛C.
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Experiments done on it:
This unit used to study heat conduction in fluids by using Fourier’s law. In this experiment the thermal conductivity of water and air will be determined and the results will be compared with known values.
The fluid whose thermal conductivity is to be determined fill the small radial clearance between a heated plug and water cooled jacket. The clearance is small enough to prevent natural convection in the fluid and the fluid is presented as a lamina of face area (πDmL) and thickness ∆r to the transfer of heat from the plug to the jacket.The plug is machined from aluminum (to reduce thermal inertia and temperature variation) and contains a cylindrical heating element whose resistance at the working temperature is accurately measured. A thermocouple is inserted into the plug close to its external surface, and the plug also has ports for the introduction and venting of the fluid under test.
The plug is held centrally in the water jacket by‘O’ rings, which seal the radial clearance, but which allow quick dismantling for cleaning. The jacket is constructed from brass and has a water inlet and drain connections and thermocouple is carefully fitted to the inner sleeve. Due to the positioning of the thermocouples and the high thermal conductivities of the materials involved, the temperatures measured are effectively the temperature of the hot and cold faces of the fluid lamina.A small console is connected by flexible cables to the plug/jacket assembly and provides for the control of the voltage supplied to the heating element. An analogue voltmeter enables the power input to be determined and a digital temperature indicator with 0.1K resolution displays the temperature of the plug and jacket surfaces.