These three parameters were combined to form the value of (Z = 2/), a key parameter in the characterization of thermoelectric materials. Until then, further development was rejected due to the low efficiency achieved, and only Abram F used semiconductor materials for thermoelectric devices. Although thermoelectric effects were discovered nearly two centuries ago, the use of thermoelectric technology is either heating or cooling, and electricity generation was only relevant in the 1950s, when this technology was successfully used for military and aerospace purposes.
Application in other fields was then rejected due to the high price of thermoelectric materials, but now it has become a reality. Thermoelectric technology presents significant advantages over conventional equipment used for cooling or power generation, as thermoelectric equipment has no moving parts (no compressors, turbines, etc. need to be installed), which makes them virtually noiseless and increases their lifespan to a great extent. laying down. Regarding the last comment, it is known that the efficiency of thermoelectric devices represents the main point that must be kept in mind, in order to make these prospects a reality.
A proper analysis of thermoelectric applications requires detailed studies on heat transfer between the thermoelectric modules, the heat source and the heat sink. Then there are different types of heat exchangers that are specifically designed to drive high heat flows from the cold and the hot side of thermoelectric devices. The chapter then studies the improvement in the efficiency of thermoelectric devices achieved with these heat exchangers.
Finally, the concept of thermoelectric self-cooling is introduced; this application uses thermoelectric technology to cool and control the temperature of a device, without consuming electricity.
Objective
Methodology
The rate of heat transfer depends on the conductivity of the partition wall and the convective heat transfer coefficient between the wall and fluids. The heat transfer rate also varies depending on boundary conditions, such as adiabatic or insulated wall conditions.
Classification of heat exchanger
Tabular heat exchanger
Double pipe heat exchanger
The reason for the higher heat transfer rate of the spiral heat exchanger is that, due to the swirling flow in a coiled tube, centrifugal forces arise, which creates the secondary flow pattern. As a result, heat transfer takes place by radial diffusion and convection. The contribution of convective heat transfer dominates the overall process and significantly increases the heat transfer rate per unit length of the tube, compared to the heat transfer rate of a straight tube of equal length.
Also, the coiled tube heat exchanger can provide a larger heat transfer area per unit volume with a compact size.
Literature Survey
Block Diagram of Counter Flow
Using the same set of tabs, the addition of heat transfer for different fluids can be studied. These tabulator variants can be used for heat transfer enhancement studies in the cooling system as well. For the same set of tabs, the heat transfer and friction characteristics can be studied for the laminar flow condition.
In this experimental study, two tube materials such as copper and aluminum are used to determine the overall heat transfer coefficient at different flow conditions. Various enhancement methods are applied to improve the thermal performance of heat transfer devices, such as treated surfaces, rough surfaces, vortex flow devices, coiled tubes, and surface tension devices. These are used to increase heat transfer by creating turbulence in the fluid flow.
The overall coefficient depends on the temperature range heat transfer flow rate and LMTD. The overall heat transfer coefficient varied due to LMTD variations using this project resulted in parallel and counter flow. The LMTD increases and then the overall heat transfer coefficient decreases for aluminum and copper tube heat exchangers. The variation in the value of the heat transfer coefficient may be due to the formation of scale on the surface of the wire, and it may also be due to variation in the fluid flow profile along the length.
In the design of the heat exchanger, the overall heat transfer coefficient is an important parameter, as it includes the conduction and convection of the heat exchanger. The rate of heat transfer can be increased by increasing the surface area by increasing the length of the tube, the smaller the diameter of the tube, the higher the heat transfer coefficient. The use of water in the copper tube heat exchanger shows an improvement in the overall heat transfer coefficient.
For this heat exchanger, the heat transfer and friction characteristics can be studied for the laminar flow condition. In future development, motor speed controller and total automation system can be added to this project. Hegab, Performance of counterflow microchannel heat exchangers subjected to external heat transfer, Heat Transfer Eng.
Saulnier, Experimental and numerical study of heat transfer in an axially flowless annular gap with an inner rotating cylinder, Int. Beer, Heat transfer in an annulus between independently rotating tubes with turbulent axial flow, Int. Al-Sadah, Finite difference analysis of heat transfer in a vertical annulus, Engineering analysis with boundary elements.
Tu, An investigation of transient mixed convection heat transfer of cold water in a tall vertical annulus with a heated rotating inner cylinder, Int.
Working Principal
Advantages
Applications
Future Scope
A switching power supply (switching power supply, switching power supply, switching power supply, SMPS or switch) is an electronic power supply that incorporates a switching regulator for efficient conversion of electricity. Unlike a linear power supply, the pass transistor of a switch-mode power supply continuously switches between low-dissipation, full-on, and full-off states and spends very little time in high-dissipation transitions, reducing wasted energy. In contrast, a linear power supply regulates the output voltage by continuously draining power in the pass transistor.
The most recognized temperature gauge is a mercury thermometer, which is used to measure the temperature of people. Copper tubing is commonly used in the construction industry for water supply lines and refrigerant lines in HVAC (heating, cooling, and air conditioning) systems. Copper tubing can be manufactured as soft or rigid copper and offers excellent corrosion resistance and reliable connections.
Hwang, Experimental study on eddy flow in concentric ring with rotating inner cylinder, KSME International Journal. 2] G.Taylor, Velocity and temperature distribution between concentrically rotating cylinders, Proceedings of the Royal Society of London. Leal, Convective thermal mass transfer in the inlet region of a concentric annulus with a rotating inner cylinder, Int.
6] Y. Lei, B. Farouk, Three-dimensional mixed convection flows in a horizontal annulus with a heated rotating inner circular cylinder, Int. W. Martin, Factors affecting the stability of viscous axial flow in rings with a rotating inner cylinder, Int. 13] P.Hsu, Inverse estimation of thermal behavior and fluid viscosity between two horizontal concentric cylinders with rotating inner cylinder, Applied Thermal Engineering.
Whitelaw, Flow of Newtonian and non-Newtonian fluids in a concentric annulus with rotation of the inner cylinder, J.
Table of component
SMPS
110-220 V AC input +-15% 12v 5 A (max) DC output, 60 W output power Terminal board design for easy connections (5-pin terminal board L, N, E, +V, - V) Short circuit protection contact Passive cooling with heat sink, solid steel housing, adjustable output voltage from (10 V to 12.5 V DC).
Pump Motor
Temperature Meter
Copper Pipe
Flow chart
Discussion
Recommendation
3] G. Taylor, The Stability of a Viscous Fluid Contained Between Two Rotating Cylinders, Royal Society of London Philosophical Transactions. Lee, Numerical computation of closed-air fluid convection between annuli of eccentrically heated horizontal rotating cylinders, Computs and Fluids.
