Heat Transfer Lab

The experimental unit is a vertical air duct into which various heating elements are inserted. An axial fan is located on top of the air duct. The fan draws in ambient air and guides it through the air duct. The air flows past a heating element and absorbs heat. Four heating elements with different geometries are available to be selected. In order to investigate free convection, two of the four heating elements can be operated outside of the air duct. The heating elements are designed in such a way to release heat only at their surface. The compact design ensures rapid heating and a short time for experiments. The experimental unit is equipped with temperature sensors at the inlet and outlet of the air duct. The air velocity is measured to determine the air flow rate. Heating power and flow rate are adjusted and displayed via the software. The unit can be connected to PC via USB. All the parameters can be obtained on the PC using software and theoretical principles can be analysed via the software provided

The experimental unit PHT-506 contains two radiation sources: a heat radiator and a light emitter. Thermal radiation is detected by means of a thermopile. Light radiation is recorded by means of a luxmeter with photodiode. Various optical elements such as apertures, absorption plates or colour filters can be set up between the emitter and the detector. All components are mounted on an optical bench. The distance between the optical elements can be read from a scale along the optical bench. Luxmeter, thermopile and light emitter can be rotated to study how the angle of incidence affects the radiation intensity. The angles are read off the angular scale. The optical elements are used to investigate the reflection, absorption and transmission of different materials at different wavelengths and temperatures. The radiant power of both emitters can be adjusted. The aim of the experiments is to check optical laws: e.g. Kirchhoff’s law of radiation, the Stefan-Boltzmann law, Lambert’s distance and direction law. The measured values are displayed digitally on the measuring amplifier. The measured values are transmitted directly to a PC via USB where they can be analysed using the software included.

Thermal conductivity λ is a temperature-dependent property of a material that indicates how well the heat propagates from a point in the material. PHT 106 can be used to study both steady and transient heat conduction. The trainer consists of a heat source and a heat sink, between which cylindrical samples made of different metals can be inserted. Each sample is fitted with 12 temperature measurement points. Electrically heated hot water circuit serves as heat source. A PID controller ensures the heating water is kept at a constant temperature. The heat sink is realized by means of a water cooling system. An elevated tank ensures a constant cooling water flow rate. A temperature jump can be generated by appropriate regulation of the cooling water flow. A PC can be used to display the transient temperature distribution in the sample over time and place. The temperatures of the sample, heating and cooling water, as well as the electrical heating power and the cooling water flow rate are displayed digitally on the switch cabinet and can be transmitted simultaneously via USB directly to a PC where they can be analysed using the software included.

The experimental unit PHT-305 can be used to determine basic laws and characteristic variables of heat conduction in solid bodies by way of experiment. The experimental unit comprises a linear and a radial experimental setup, each equipped with a heating and cooling element. Different measuring objects with different heat transfer properties can be installed in the experimental setup for linear heat conduction. The experimental unit includes with a display and control unit. Sensors record the temperatures at all relevant points. The measured values are read from digital displays and can be transmitted simultaneously via USB directly to a PC, where they can be analysed using the software included

The trainer PHT-503 is used to study the convection heat transfer and effect of different geometries of the transfer area on heat transfer. Models such as tube bundles, externally heated tubes and internally heated cylinders are considered. In addition measurement of convective heat transfer with free convection in the air duct. The trainer consist of an air duct with fan which is the measuring section, in which the model of different geometries can be inserted quickly and conveniently with the help of quick-release fasteners. The air flows past the model, heats up and then exits through an air duct. A streamlined inlet element in the air duct provides a homogeneous flow for conducting the experiment. The flow rate is set via a throttle valve at the fan outlet. The model of the shell & tube heat exchanger includes two interchangeable tube bundles with different geometries. A heating element, which can be positioned anywhere in the tube bundle, simulates a heated tube. In this way, convective heat transfer can be determined depending on the tube posi-tion. Other models: PHT 503.01 (Heat transfer in pipe in parallel flow) PHT 503.02 (Heat transfer in pipe in mixed flow) PHT 503.03 (Heat transfer in pipe in a tube) Are available as optional accessories. A Pitot tube and a pressure gauge are used to determine the velocity distribution in front of and behind the models. Heat-ing power and volumetric flow rate can be adjusted. The heating power and the temperatures of air and heater are dis-played digitally.

The Experimental unit can be used to demonstrate the different condensation processes using two tubular shaped water-cooled condensers made of different materials. Dropwise condensation can be demonstrated by means of the condenser with a polished gold-plated surface. Film condensation forms on the matt copper surface of the second condenser, thus making it possible to examine film condensation. The tank can be evacuated via a water jet pump. The boiling point and the pressure in the system are varied by cooling and heating power. Sensors record the temperature, pressure and flow rate at all relevant points. The measured values can be read on digital displays. At the same time, the measured values can also be transmitted directly to a PC via USB. The data acquisition software is included. The heat transfer coefficient is calculated from the measured values.

The apparatus consists of a container containing water. The heating surface is in the form of a Nichrome heater wire completely submerged in the water. There is another heater submerged in the water to initially heat the water upto the required temperature to study the critical heat flux phenomenon at various temperatures of water in cylindrical shell. The temperature of the water in the cylindrical shell is measured with the help of a temp sensor. Electrical supply to the test heating wire is given through a dimmerstat. And the power input is measured with a voltmeter and an ammeter.

Plate types Heat Exchanger are popular in process industries because they occupy less space and offer reasonable temperature drop. Valves are provided to control the flow rates of hot and cold water. Flow rates of hot and cold water are measured using Rotameters. A magnetic drive pump is used to circulate the hot water from a re-cycled type water tank, which is fitted with heater and Digital Temperature Controller.

Shell and Tube Heat Exchanger are popular in process industries because they occupy less space and offer reasonable temperature drop. The apparatus consists of fabricated shell, inside which tubes with baffles on outer side are fitted. The present set up is a 1-2 heat exchangers, with cold water flows through shell. Valves are provided to control the flow rates of hot and cold water. Flow rates of hot and cold water are measured using Rotameters. A magnetic drive pump is used to circulate the hot water from a re-cycled type water tank, which is fitted with heater and Digital Temperature Controller.

Heat exchanger is a device in which heat is transferred from one fluid to another. The apparatus consists of a concentric tube heat exchanger. Hot water flows through inner tube in one direction only and cold water flows through the outer tubes. Direction of cold fluid flow can be changed from parallel or counter to hot water so that unit can be operated as parallel or counter flow heat exchanger. Flow rates of hot and cold water are measured using Rota meters. A magnetic drive pump is used to circulate the hot water from a re-cycled type water tank, which is fitted with heaters and Digital Temperature Controller.

Condensation is a phase change heat transfer process occurring in many industrial applications, such as in steam power plants, refrigeration plants etc. Thus this is one of the important heat transfer process as present in mechanical and chemical engineering applications. The condensation of vapour on a surface is of two types: 1. Drop wise Condensation, 2. Film wise Condensation. This setup is designed for determining heat transfer co-efficient of two types of condensation and for visualization of these processes. It consists of a vertical frame. Condensation tubes are fitted inside compact glass cylinder. Steam generator is fitted at the backside of the cylinder. Steam comes directly from generator to the cylinder. Valves are fitted to control flow rate of water in individual tubes. Digital Temperature Indicator monitors the temperatures. Pressure gauge and Rotameter can observe steam pressure and cold water flow rates respectively. A Digital temperature Controller is provided for controlling the temperature of Steam. Water level indicator is provided in steam generator. Condensate is measured by a measuring cylinder.

The apparatus is designed to determine the Stefan Boltzmann constant. The apparatus consists of a hemisphere fixed to a Bakelite plate, the outer surface of which forms the jacket to heat it. Hot water to heat the hemisphere is obtained form a hot water tank, which is fixed above the hemisphere. The copper test disc is introduced at the center of hemisphere. The temperatures of hemisphere and test disc are measured with the help of temperature sensors.

The present Set-up is designed to measure the emissivity of test plate. The test plate comprises of a mica heater sandwiched between two circular plates. Black plate is identical with test plate, but its surface is blackened. As all the physical properties, dimension and temperature are equal; heat losses from both plates will be same except radiation loss. Hence the input difference will be due to difference in emissivity. Both plates are supported on individual brackets in a enclosure with one side glass to ensure steady atmospheric conditions. Temperature Sensors are provided to measure the temperature of each plate and surrounding. Electric Supply is given to heaters through separate variacs so that temperatures of both can be kept equal and is measured with Digital Voltmeter and Digital Ammeter.

The setup consists of a brass tube fitted in a rectangular duct in a vertical position. The duct is open at the top and bottom, and forms an enclosure that serves the purpose of undisturbed surrounding. One side of the duct is fitted with a transparent acrylic window for visualization. An electric heating element is kept in the vertical tube that in turns heats the tube surface. The heat is lost from the tube to the surrounding air by natural convection. The temperature of the vertical tube is measure by temperature sensors and displayed by a Digital Temperature Indicator with multi-channel switch. The heat input to the heater is measured by a Digital Ammeter and a Digital Voltmeter and is varied by a variac. The tube surface is polished to minimize the radiation losses.

The set up is designed to study the heat transfer in a pin fin. It consist of pin type fin fitted in a duct. A fan is provided on one side of duct to conduct experiment under forced draft condition. Air flow rate can be varied. A heater heats one end of fin and heat flows to another end. Digital Temperature indicator measure temperature distribution along the fin.

The apparatus is designed to determine thermal conductivity of different liquids. The apparatus consists of a heater. The heater heats a thin layer of liquid. A cooling plate removes heat through liquid layer, ensuring unidirectional heat flow. Temperature is measured across the liquid layer and complete assembly is properly insulated. A proper arrangement for changing the liquids is provided. The whole assembly is kept in a chamber.

The set-up is designed to determine thermal conductivity of insulating materials in the form of slab. The apparatus consists of main central heater and ring guard heater, sandwiched between the specimens. Cooling plates are provided on either side of the specimen. Two identical specimens are clamped between a heater that ensures unidirectional heat flow through specimen. The whole assembly is kept in chamber and insulated by ceramic wool insulation around the set-up.

It is a super-conducting device and involves the transfer of heat by boiling and condensation of a fluid and hence transfer of heat takes place under nearly isothermal condition. In this apparatus the comparison of heat pipe with the copper pipe as good conductor of heat and with the stainless steel pipe as same material of construction is made. It consists of three identical cylindrical conductors in respect of geometry. One end of these is heated electrically while there are small capacity tanks acting as heat sinks at the other end. The unit consists of a heat pipe, a copper pipe and a stainless steel pipe. The performance of the heat pipe as a super-conducting device can be studied well in terms of the temperature distribution along the length at a given instant and can be compared with other two members. Nearly isothermal temperature distribution and fast rise of temperature in heat sink tank reveals the heat pipe superiority over the conventional conductors.

The setup is designed and fabricated to study lagging phenomenon in case of pipes. It consists of three concentric pipes of small thickness as compared to diameter and are arranged concentrically, and closed with the help of two discs. Two different insulating materials fill the annuli between the cylinders. Temperature Sensors are fitted to measure the temperature of pipe walls for radial outward heat flow measurement. Inside the inner pipe, a Nichrome wire heater is placed axially. Heat input to the heater is given through a variac and measured by Digital Voltmeter and Digital Ammeter.

The setup consists of a heater sandwiched between two sets of slabs. Three types of slabs are provided on either sides of heater, which forms a composite structure. A small hand press frame is provided to ensure the perfect contact between the slabs. A variac is provided for varying the input to the heater. Digital Voltmeter and Digital Ammeter display the heat input. Heat produced by heater flows axially on both the sides. Temperature Sensors are embedded at the interfaces of slabs to determine the temperature gradient. The experiment can be conducted at various values of heat input and calculation can be made accordingly.