In cross flow type of heat exchangers, the fluids flow in directions normal to each other. Cross flow heat exchangers made in aluminum are common as radiators in vehicles. A vehicle needs more power and space for comfort purpose. So, a countercurrent heat exchanger (HEX) is need to be shifted. It may be shift on the roof of the vehicle compartment.
Heat Exchanger is a device that is used to transfer thermal energy between two fluids or more fluids , between a solid surface and a fluid, or between solid particulates and a fluid, at different temperatures and in thermal contact. In heat exchangers, there are usually no external heat and work interactions. Typical applications involve heating or cooling of a fluid stream of concern and evaporation or condensation of single or multi component fluid streams. In other applications, the objective may be to recover or reject heat, pasteurize, fractionate, distill, concentrate, crystallize, or control a process fluid. In a few heat exchangers, the fluids exchanging heat are in direct contact.
They show that the standard counter-current heat exchanger is the best first approximation to optimal heat exchange conditions in practice, as it has, mqualitatively the same properties as the optimal solutions presented in their study; when the temperature difference Th – Tc between the hot and the cold fluids is approximately constant. In the present study the authors assume Th – Tc to be constant throughout the heat exchanger, for the sake of simplicity. Hesselgreaves (2000) studies entropy generation in heat exchangers, and develops a new relationship for optimising balanced counter-flow heat exchangers for a ‘long’ duty, i.e. with significant temperature changes of the working fluids. Yilmaz et al.
Flexible plastics are used for fabrication of the heat transfer tubes; PVC and silicone are some common materials used for this (John C. Chato). When considering the heat transfer characteristics, higher diameter pipes are preferred. Because they provide high heat transfer area and allow high refrigerant flow rates at low pumping heads. But usage of tubes with larger diameter increases the rigidity of the kit which is undesirable for convenient movement of the wearer. Therefore LCVGs uses smaller diameter tubes with low wall thickness.
Three heating modes were considered: assisting flow, opposing flow and heating from below. Results for Richardson numbers equal to 0.1 and 100, Re= 100 and 1000 and aspect ratio in the range 0.1 -1.5 were reported. It was shown that that maximum temperature values were decreased as the Reynolds and the Richardson number increased. The effect of the ratio of channel height to the cavity height was found to play a significant role on streamline and isotherm patterns for different heating configuration. The investigation showed that opposing forced flow configurations had the highest thermal performance in terms of both maximum temperature and average Nusselt number.
ELECTRIC HEATER Sachin Pandey Roll No: 712CH1099 Introduction: An electric heater is a device that converts electrical current to heat energy. The basic principle followed by the heater is Joule heating and the main heating element responsible for this heating effect is a resistor. When an inductive current passes through these resistors heat energy is produced due to the ‘Joule losses’ caused by the eddy currents induced inside the heater. There can be different types of electric heater based on the type of the resistor used or based on the enclosure used for the heater. In this article the various types of electric heaters based on the type of resistor and the enclosure are discussed in brief.
Chemical kinetics and reactor design are vitally important in producing almost all industrial chemicals. In order to choose a reaction system that suit the chemical plant to operate in highest efficiency and safest manner are the main factors contribute to the success of a chemical plant. In another word, a CSTR is run at steady state with continuous flow of reactants and products. The feed of CSTR is assumed as a homogeneous composition throughout the reactor that indicates the exit stream and inside the tank have the same composition. The reactants and products will be constantly added and withdrawn.
Delaunay Triangulation The increase in the demand for positional information and the modeling of this information gave birth to an increase of interpolation which is the production of intermediary values. This method is progressed by the selection of exemplary points on the surface. The surface modeling could be done a by a single algorithm or it could be divided into geometric shapes and then apply the algorithm. Especially, the constitution of links between the selected points to form triangles is a very common application in the handling of irregular surfaces. Widely used in computing in a variety of applications, Delaunay triangulation method is one of the most effective methods among all algorithms for computing triangulation.
3.1 Heat Pump A heat pump as shown in Figure 3.1 is a device that provides heat energy from a source of heat to a destination called a "heat sink". Heat pumps are designed to move thermal energy opposite to the direction of spontaneous heat flow by absorbing heat from a cold space and releasing it to a warmer one. A heat pump uses some amount of external power to accomplish the work of transferring energy from the heat source to the heat sink. While air conditioners and freezers are familiar examples of heat pumps, the term "heat pump" is more general and applies to many HVAC (heating, ventilating, and air conditioning) devices used for space heating or space cooling. When a heat pump is used for heating, it employs the same basic refrigeration-type cycle used by an air conditioner or a refrigerator, but in the opposite direction - releasing heat into the conditioned space rather than the surrounding environment.
They used modified time function for analysis of single-phase liquid or gas wells performance. One of the weaknesses of their method is that despite of the underestimation or overestimation of reserves that results when the method is applied, it completely neglects the data of flowing pressure. Moreover, it also neglects the changing production situation and therefore is not able to always produce reliable evaluations of recoverable hydrocarbons. Moreover, the gas reserves are usually underestimated due to the varying gas properties that are not