Condensation is the change in phase from the vapor state to the liquid or solid state. It can be considered as taking place either within a bulk material or on a cooled surface and is accompanied by simultaneous heat and mass transfer. Condensation plays a significant role in the heat rejection parts of the Rankine power cycle and the vapor compression refrigeration cycle, which generally involve pure substances. Dehumidification in air conditioning and the production of liquefied petroleum gases, liquid nitrogen and liquid oxygen and examples in which condensation in a mixture takes place. Condensation on cooled surface occurs in one of two ways: Film or Drop wise condensation.
In film condensation the liquid condensation forms a continuous film which covers the surface and takes place when the liquid wets the surface. This film flows over the surface under the action of gravity or other body surface, surface tension and shear stresses due to vapor flow. Heat transfer to the solid surface takes place through the film which forms the greatest part of the thermal resistance.
In Drop wise condensation the vapor impinges on the cool wall, reducing its energy and thereby liquidizing and forming drops which grow by direct condensation of vapor on the drops and by coalescence with neighboring drops until the drops are swept off the surface by the action of gravity or other body forces, surface tension and shear stresses due to Vapour flow. As the drops move they coalesce with other droplets in their path, sweeping a portion of the surface clean so that condensation can begin. The details of drop wise condensation are not completely understood bit it is known to take place under circumstance where the liquid does not wet the surface.
This system is designed to study the thermal radiation of a given two identical specimen (made out of homogeneous material) one with black coating and other without coating. This system helps students to study the emissivity of non-black surface during the charge. The setup consists of two circular brass plates identical in size and is provided with heating coils at the bottom. One of the brass plates is coated black in color, which is called black body and the other gray body. The plates are mounted on asbestos cement sheet and surrounded by a wooden enclosure so as to provide undisturbed natural convection surroundings. The heat input to the heater is varied by Variac and is measured by Ammeter & Voltmeter. A temperature indicator with a selector switch is provided to measure the various temperatures of the specimen.
The apparatus consists of a blower to supply air. The air from the blower passes through a flow passage, heater and then to the test section. Airflow is measured by an orifice meter placed near the test section. A band heater is placed around the tube, the heater heats the air which is flowing inside the tube and the heat input can be controlled using a Variac provided on the panel. Temperature of the air at the inlet, outlet and surface temperatures of the test specimen are measured using thermocouples and are indicated with the help of a temperature indicator. A bypass valve at the discharge of the blower is provided to conduct the experiments in different Reynolds numbers.
The apparatus consists of a metal pipe with two layers of insulation. An electric heating coil wound on a silica rod is placed at the center. The ends are thickly insulated to prevent heat loss so that, heat flow only in a radial direction. Three thermocouples each are placed at different radii to measure the temperature distribution within the cylinder.
Convection heat transfer occurs by the movement of fluid particles. If the motion of fluid particles occurs by the variation of density of the fluid due to temperature difference, then the heat transfer process is called free or natural convection. The apparatus consists of a vertical stainless steel tube enclosed in a rectangular duct; front side of the duct is made of transparent section to facilitate visual observation. An electrical heating element embedded in a copper tube acts as the heat source. The surface temperature is measured at different heights using thermocouples. The surface of the tube is polished to minimize radiation losses. A voltmeter and an ammeter enable the determination of wattage dissipated by the heater.
This system provides the information regarding the heat transfer from the hot zone to the chamber. Thus reducing the temperature of the source and spreading the same through pin type fin and further provides the knowledge regarding the distribution of temperature along the length of fin in forced convention and also to facilitate the comparison of fins of brass material. Further, it also enables the student to compare theoretical and practical results. Thermocouples are fitted on the pin for measuring the various temperatures. The heat input to the heater is varied by Variac and is measured by Ammeter & Voltmeter.
This apparatus enables the student to study the characteristics of composite structures and its heat transfer ability across the composite walls by altering the combination of slabs. The apparatus consists of three slabs of different materials of same thickness. The slabs are brought together in contact. The three slabs are brass, M.S and asbestos. One surface of the slab is electrically heated and the other end is cooled, .the temperatures of the slabs are measured using thermocouples and are indicated by temperature indicator. The power Input to the heater is measured by Voltmeter and Ammeter.
The apparatus consists of a concentric tube heat exchanger. The hot fluid (Hot water) is obtained from an electric geyser and it is made to flow through the inner tube. The cold fluid (cold or ambient temperature water) is made to flow through the outer tube. When the cold fluid and the hot fluid is made to pass in the same direction, the process is called parallel flow, when the cold fluid and the hot fluid is made to flow in opposite direction the process is called counter flow. Temperatures at the inlet and outlet of the fluids are measured using thermocouples and are connected to a digital temperature indicator.
This equipment allows student to fully investigate the performance and characteristic of a shell and multi tube heat exchanger. It consists of 12 tubes of 12mm outside diameter and the effective length of the tube is 1000mm with two tube pass. The shell is made of stainless steel having inside diameter of 150mm with 6 segmental baffles. The water flow rate is measured using a Rota meter. Thermocouples are provided for measuring the inlet and outlet temperature hot and cold fluids.
This apparatus is designed to determine Stefan Boltzman constant for radiation heat transfer. The apparatus consists of a flanged copper hemisphere fixed on a flat non-conducting plate. A test disc made of copper is fixed to the plate, thus the test disc is completely enclosed by the hemisphere. The outer surface of the hemisphere is enclosed in a vertical water jacket used to heat the hemisphere to a suitable constant temperature. Three Cr-Al type thermocouples are attached at three strategic places on the surface of the hemisphere to obtain the temperatures. The disc is mounted on a Bakelite sleeve which is fitted in a hole drilled at the center of the base plate. Another Cr-Al thermocouple is fixed to the disc to record its temperature.
The apparatus consists of two concentric copper spheres made out of copper. A heating coil is provided in the inner sphere. The empty space between the inner and outer spheres are filled with insulting powder whose thermal conductivity is to be determined. The heat input of the heater can be varied using a Variac provided on the panel. Necessary thermocouples are provided in the setup to study the thermal conductivity of insulating powder.
This equipment allows student to determine the thermal conductivity of a poor conducting liquid, like liquid glycerin. All the heat transfer experimental setup is of single unit, consists of a Powder Coated M.S Panel.
The apparatus consists of a metal bar; one end of the metal bar is heated by an electric heating coil while the other end projects inside the cooling water jacket. The middle portion of the rod is surrounded by an insulating material like asbestos to minimize lateral heat transfer from the rod and thus ensure a more nearly constant temperature gradient throughout the length of the rod. The temperature of the bar is measured at five different locations while the radial temperature distribution is measured separate thermocouples at two different sections in the insulating shell. The heater is provided with a dimmer stat for controlling the heat input, water can be circulated through the jacket and its flow rate and temperature rise can be noted down.
This equipment allows student to determine the thermal conductivity of a poor conducting material, like asbestos sheet by guarded hot plate method. The test specimen is placed on a flat plate heater assembly consisting of an electrically heated inner plate (main heater) surrounded by a guard heater. The guard heater is carefully controlled to maintain the same temperature on both sides of the gap separating the main and the guard heaters. This prevents lateral heat flow from the main heater and ensures that all heat energy flows in the direction of the specimen. On the opposite side of the specimen are additional flat plate heaters (the "cold" plate) that are controlled at a fixed temperature selected by the operator. For a given heat input to the main heater, the hot plate assembly rises in temperature until the system reaches equilibrium. The final hot plate temperature depends on the electrical power input, the thermal resistance of the specimen, and the temperature of the cold plate. The average thermal conductivity, k, of the specimen is determined from the Fourier heat flow equation.
The apparatus is designed to reveal clearly the conducting material. It consists of three identical cylindrical pipes, one end of the pipes is heated electrically and the other end is cooled by water. Thermocouples are embedded along the lengths to measure the temperature distribution. Heat input is measured by digital voltmeter and ammeter. The temperatures at various points are measured by thermocouples and indicated in a digital temperature indicator.
Heat conduction is the transfer of thermal energy between neighboring atoms and molecules in a solid or in a fluid at rest. The heat transport is substance-bound. The effect of pure heat conduction is hindered in fluids by convection effects. This can be prevented by enclosing the fluids in gaps. This experimental unit serves to examine heat conduction properties of various fluids. The core element of the experimental unit is a cylindrical heat exchanger with a heated inner cylinder made of aluminium and a water-cooled jacket. There is a ring-shaped gap between the inner cylinder and the jacket, which is completely filled with the fluid or gas to be examined. The width of the gap is such that the heat transfer by convection is negligible. Due to the low temperature level and polished surfaces, radiation is also negligible. The thermal conductivities k of various fluids such as water, oil, air, oxygen or carbon dioxide can be determined in experiments. Sensors record the temperatures and the consumed heating power at all relevant points. The measured values can be read in the computer software.