CHAPTER 1 INTRODUCTION 1.1 Introduction Heat exchangers have always been an important part to the lifecycle and operation of many systems. A heat exchanger is a device built for efficient heat transfer from one medium to another in order to carry and process energy. Typically one medium is cooled while the other is heated. They are widely used in petroleum refineries, chemical plants, petrochemical plants, natural gas processing, air-conditioning, refrigeration, and automotive applications . Shell-and-tube heat exchangers (STHEs) are the most widely type of heat exchanger used in industrial processes as in nuclear power stations as condensers, steam generator in pressurized and water reactor plants, and feed water heaters.
As most of the zones are cleaned frequently and thoroughly using strong cleaning agents such as corrosive agents, alkalis and dry ice, the materials used need to be suitable. • Temperature Resistant. The F&B components include high temperature zones in baking areas, pasteurization and sterilization and low temperature zones in refrigerated areas. These extreme temperatures can be especially hard on cables, glands and components and special temperature resistant materials need to be used to provide adequate
Regenerative type: The heat exchanger in which hot and cold fluids occupy the same space containing a matrix of material that works alternatively as a sink or source for heat flow is known as regenerative type of heat exchanger. Evaporative type: The exchanger such as cooling tower in which a liquid is cooled evaporative in the Same space as coolant is known as evaporative type of heat exchanger Among all the three kinds of heat exchanger the most important heat exchanger is recuperative type HEX. According to the flow of the fluid these are of the following types : • Parallel-flow • Counter-flow • Cross-flow Parallel–flow Heat exchanger: The exchanger in which both the fluids flow in the same direction. Counter-flow : The exchanger in which the fluids flow in the opposite direction. Cross-flow: The exchanger in which the fluids are perpendicular to each other is known as the cross flow heat
The formulation of these lubricants were complicated that combine ingredients such as base oil (mostly mineral base oil), emulsifiers, anticorrosive agent, antioxidant agent, biocides, surfactants and much more. The use of additives in the making of lubricant can be one of the
Viscosity: This is an internal property of fluid that offers resistance to flow. Thermal conductivity: This is the quantity of heat transmitted through unit thickness in direction normal to a surface. Specific heat: This is amount of heat per unit mass required to raise the temperature by one kelvin 1.3 Literature Review Various researchers have carried out investigations into the effect of mixed convective flows in rectangular enclosures by using analytical, experimental, and numerical
This medium can damage the rubber if the temperature is rise. These changes are caused by two mechanism The elastomer absorbs a medium. Plasticizers and other components of the compound are dissolved and extracted or leached out by the media. Therefore there is need of careful selection of base polymer which must compatible with the fluid but also must heat resistance. Two materials are selected which have good compatibility as well as heat resistance.
Loads on the rock will affect the core’s permeability to fluids, so it is important to duplicate them during testing. The injection pressure at the core face is measured using a pressure transducer and the gas flow rate is measured using a precision mass flow meter. An excel spreadsheet calculation template allows for calculation of gas
Vapor Compression (VC) (Figure 7): a working fluid is evaporated at the condenser (by condensing another fluid, such as the top product from a distillation or stripping column). The working fluid is then compressed to a higher temperature (saturation) condensed in the reboiler (often determined by the specific conditions and materials within a process) and cooled down by expansion over a throttle valve to a (saturation) temperature below the condenser temperature. One of the most important design variables when using a vapor compression heat pump is the choice of an adequate working fluid. An example that can be seen in industry the ethylene-ethane separation using propylene as working fluid (Bruinsma & Spoelstra, 2010) Thermo-acoustic heat
When the flow directions are parallel, the streams may flow in the same or in opposite sense. So there are three primary flow arrangements for a plate fin heat exchanger – (i) parallel flow, (ii) counter-flow and (iii) cross flow. Thermodynamically, the counter-flow arrangement provides the highest heat (or cold) recovery, while the parallel flow geometry gives the lowest. While the cross flow arrangement, gives an intermediate thermodynamic performance, by offering superior heat transfer properties and easier mechanical layout. Under some circumstances, a hybrid cross – counter-flow geometry provides greater heat (or cold) recovery with superior heat transfer performance.
The chemical composition, the crystal structure, and the magnetic compound states are among the most significant substantial parameters that determine its MCE . The materials exhibit large, reversible temperature changes in response to changing magnetic fields usually referred to as Magneto-caloric Materials . Two types of the magnetic phase changes can occur : First Order Magnetic Transition