Imperfections in Solids, Lecture Notes-Imperfections in Solids, PDF, kb Properties of Metals, Lecture Notes-Mechanical Properties of Metals, PDF, . NPTEL provides E-learning through online Web and Video courses various streams. Mechanical Measurements and Metrology. Introduction to the Study of Mechanical Measurement · Errors in Measurement · Errors in Measurement( Contd.
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NPTEL · Mechanical Engineering; Basic Thermodynamics (Web); Downloads Fundamental Concepts & Definitions, Problems and Solutions, PDF, kb. Definition of Stress. Consider a small area δA on the surface of a body (Fig. ). The force acting on this area is δF. This force can be resolved into two. L1: Fundamentals of Engineering Mechanics. Imagine the following situations: (a ) You have to design a car, which can run at a speed of km/hr on an.
In parallel-flow heat exchangers, the two fluids enter the exchanger at the same end, and travel in parallel to one another to the other side. In counter-flow heat exchangers the fluids enter the exchanger from opposite ends. The counter current design is the most efficient, in that it can transfer the most heat from the heat transfer medium per unit mass due to the fact that the average temperature difference along any unit length is higher. See countercurrent exchange. In a cross-flow heat exchanger, the fluids travel roughly perpendicular to one another through the exchanger.
Lecture Notes-Imperfections in Solids. Lecture Notes-Mechanical Properties of Metals.
Lecture Notes-Diffusion. Lecture Notes-Dislocations and Strengthening Mechanisms. Lecture Notes-Phase Diagrams. Lecture Notes-Failure. Lecture Notes-Applications and Processing of Ceramics. Lecture Notes-Applications and Processing of Polymers. Lecture Notes-Composites. Lecture Notes-Corrosion and Degradation of Materials. Lecture Notes-Electrical Properties. Lecture Notes-Thermal Properties.
Lecture Notes-Magnetic Properties. Lecture Notes-Optical Properties. Atomic Structure,Interatomic Bonding and structure of Crystalline solids. Mechanical Properties of Metals. Dislocations and Strengthening Mechanisms. Applications and Processing of Metals and Alloys. Module Name Download. History Of Refrigeration? Development Of Refrigerants And Compressors. Review of fundamental principles? Part I. Part II.
Review of fundamentals: Fluid flow. Heat and Mass transfer. Methods of producing Low Temperatures. Air cycle refrigeration systems. Vapour Compression Refrigeration Systems. The triangular patterns are employed to give greater heat transfer as they force the fluid to flow in a more turbulent fashion around the piping.
Square patterns are employed where high fouling is experienced and cleaning is more regular. Baffle Design: baffles are used in shell and tube heat exchangers to direct fluid across the tube bundle. They run perpendicularly to the shell and hold the bundle, preventing the tubes from sagging over a long length. They can also prevent the tubes from vibrating.
The most common type of baffle is the segmental baffle. The semicircular segmental baffles are oriented at degrees to the adjacent baffles forcing the fluid to flow upward and downwards between the tube bundle. Baffle spacing is of large thermodynamic concern when designing shell and tube heat exchangers. Baffles must be spaced with consideration for the conversion of pressure drop and heat transfer.
Having baffles spaced too closely causes a greater pressure drop because of flow redirection. Consequently, having the baffles spaced too far apart means that there may be cooler spots in the corners between baffles.
It is also important to ensure the baffles are spaced close enough that the tubes do not sag. The other main type of baffle is the disc and doughnut baffle, which consists of two concentric baffles.
An outer, wider baffle looks like a doughnut, whilst the inner baffle is shaped like a disk. This type of baffle forces the fluid to pass around each side of the disk then through the doughnut baffle generating a different type of fluid flow. Fixed tube liquid-cooled heat exchangers especially suitable for marine and harsh applications can be assembled with brass shells, copper tubes, brass baffles, and forged brass integral end hubs.
Conceptual diagram of a plate and frame heat exchanger.
A single plate heat exchanger An interchangeable plate heat exchanger applied to the system of a swimming pool Plate heat exchangers[ edit ] Main article: Plate heat exchanger Another type of heat exchanger is the plate heat exchanger. These exchangers are composed of many thin, slightly separated plates that have very large surface areas and small fluid flow passages for heat transfer.
Advances in gasket and brazing technology have made the plate-type heat exchanger increasingly practical. In HVAC applications, large heat exchangers of this type are called plate-and-frame; when used in open loops, these heat exchangers are normally of the gasket type to allow periodic disassembly, cleaning, and inspection.
There are many types of permanently bonded plate heat exchangers, such as dip-brazed, vacuum-brazed, and welded plate varieties, and they are often specified for closed-loop applications such as refrigeration.
Plate heat exchangers also differ in the types of plates that are used, and in the configurations of those plates. When compared to shell and tube exchangers, the stacked-plate arrangement typically has lower volume and cost. Another difference between the two is that plate exchangers typically serve low to medium pressure fluids, compared to medium and high pressures of shell and tube. A third and important difference is that plate exchangers employ more countercurrent flow rather than cross current flow, which allows lower approach temperature differences, high temperature changes, and increased efficiencies.
Plate and shell heat exchanger[ edit ] A third type of heat exchanger is a plate and shell heat exchanger, which combines plate heat exchanger with shell and tube heat exchanger technologies. The heart of the heat exchanger contains a fully welded circular plate pack made by pressing and cutting round plates and welding them together. Nozzles carry flow in and out of the platepack the 'Plate side' flowpath.
The fully welded platepack is assembled into an outer shell that creates a second flowpath the 'Shell side'. Plate and shell technology offers high heat transfer, high pressure, high operating temperature , uling and close approach temperature. In particular, it does completely without gaskets, which provides security against leakage at high pressures and temperatures.
Adiabatic wheel heat exchanger[ edit ] A fourth type of heat exchanger uses an intermediate fluid or solid store to hold heat, which is then moved to the other side of the heat exchanger to be released. Two examples of this are adiabatic wheels, which consist of a large wheel with fine threads rotating through the hot and cold fluids, and fluid heat exchangers. Plate fin heat exchanger[ edit ] Main article: Plate fin heat exchanger This type of heat exchanger uses "sandwiched" passages containing fins to increase the effectiveness of the unit.
The designs include crossflow and counterflow coupled with various fin configurations such as straight fins, offset fins and wavy fins.