For ic engine......equation for co-efficient of heat transfer

There have been a number of studies on air-cooling  of aircooled engine fins. Table 1 shows the experimental  cylinders
and air velocity investigated by other researchers. They acquired
data on cylinder cooling at relatively high air velocity. Some
researchers tested at air velocity from 7.2 to 72 km/h to enable
the fin design of motorcycle engines but did not investigate
temperature distribution in the fin circumference in detail. An
experimental equation of the fin surface heat transfer coefficient
using a copper cylinder at air velocity from 32 to 97 km/h was
derived by the researchers as follows.



α = 241.7{ 0.0247 − 0.00148 (h^0.8 /p^0.4) }u^0.73             (1)



where,
= Fin surface heat transfer coefficient, W/m^2*k , h = Fin length,
mm, p = Fin pitch, mm, u = Air velocity, km/h


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why cooling of ic engine requried.....??

               We know that in case of Internal Combustion engines, combustion of air and fuel takes
place inside the engine cylinder and hot gases are generated. The temperature of gases
will be around 2300-2500°C. This is a very high temperature and may result into burning
of oil film between the moving parts and may result into seizing or welding of the same.
So, this temperature must be reduced to about 150-200°C at which the engine will work
most efficiently. Too much cooling is also not desirable since it reduces the thermal
efficiency. So, the object of cooling system is to keep the engine running at its most
efficient operating temperature

.
              It is to be noted that the engine is quite inefficient when it is cold and hence the cooling
system is designed in such a way that it prevents cooling when the engine is warming up
and till it attains to maximum efficient operating temperature, then it starts cooling.
It is also to be noted that :
                    (a) About 20-25% of total heat generated is used for producing brake power
                         (useful work).
                    (b) Cooling system is designed to remove 30-35% of total heat.
                    (c) Remaining heat is lost in friction and carried away by exhaust gases.
                          Objectives

Heat engines generate mechanical power by extracting energy from heat flows, much as a water wheel extracts mechanical power from a flow of mass falling through a distance. Engines are inefficient, so more heat energy enters the engine than comes out as mechanical power; the difference is waste heat which must be removed. Internal combustion engines remove waste heat through cool intake air, hot exhaust gases, and explicit engine cooling.

Engines with higher efficiency have more energy leave as mechanical motion and less as waste heat. Some waste heat is essential: it guides heat through the engine, much as a water wheel works only if there is some exit velocity (energy) in the waste water to carry it away and make room for more water. Thus, all heat engines need cooling to operate.

Cooling is also needed because high temperatures damage engine materials and lubricants. Internal-combustion engines burn fuel hotter than the melting temperature of engine materials, and hot enough to set fire to lubricants. Engine cooling removes energy fast enough to keep temperatures low so the engine can survive.

Some high-efficiency engines run without explicit cooling and with only accidental heat loss, a design called adiabatic. For example, 10,000 mile-per-gallon "cars" for the Shell economy challenge are insulated, both to transfer as much energy as possible from hot gases to mechanical motion, and to reduce reheat losses when restarting^{[citation needed]}. Such engines can achieve high efficiency but compromise power output, duty cycle, engine weight, durability, and emissions.




It is important for an air-cooled engine to utilize fins for effective engine cooling to maintain uniform temperature in the 
cylinder periphery. Many experimental works has been done to improve the heat release of the cylinder and fin efficiency.  In 
this study, heat release of an IC engine cylinder cooling fins with six numbers of fins having pitch of 10 mm and 20 mm are 
calculated numerically using commercially available CFD tool Ansys Fluent. The IC engine is initially at 150  and the heat 
release from the cylinder is analyzed at a wind velocity of 0 km/h. The heat release from the cylinder which is calculated 
numerically is validated with the experimental results. With the help of the available numerically results, the design of the I.C 
engine cooling fins can be modified for improving the heat release and efficiency. 







         

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Generation of Heat and Power both in power plant(Cogeneration)

Cogeneration

Cogeneration (also combined heat and power, CHP) is the use of a heat engine^[1] or a power stationto simultaneously generate both electricity and useful heat.

All thermal power plants emit a certain amount of heat during electricity generation. This can be released into the natural environment through cooling towers, flue gas, or by other means. By contrast, CHP captures some or all of the by-product heat for heating purposes, either very close to the plant, or—especially in Scandinavia and eastern Europe—as hot water for district heating with temperatures ranging from approximately 80 to 130 °C. This is also called Combined Heat and Power District Heating or CHPDH. Small CHP plants are an example of decentralized energy.^[2]

Cogeneration was practiced in some of the earliest installations of electrical generation. Before central stations distributed power, industries generating their own power used exhaust steam for process heating. Large office and apartment buildings, hotels and stores commonly generated their own power and used waste steam for building heat. Because of the economies and high cost of early purchased power, these combined heat and power operations continued for many years after utility electricity became available.^[3] Cogeneration is still common in pulp and paper mills, refineries and chemical plants.

In the United States, Con Edison distributes 66 billion kilograms of 350 °F/180 °C steam each year through its seven cogeneration plants to 100,000 buildings in Manhattan—the biggest steam district in the United States. The peak delivery is 10 million pounds per hour (corresponding to approx. 2.5 GW).^[4][5]

Other major cogeneration companies in the United States include Recycled Energy Development^[6] and leading advocates include Tom Casten andAmory Lovins.

By-product heat at moderate temperatures (212-356°F/100-180°C) can also be used in absorption chillers for cooling. A plant producing electricity, heat and cold is sometimes calledtrigeneration^[7] or more generally polygeneration plant. Cogeneration is a thermodynamically efficient use of fuel. In separate production of electricity, some energy must be rejected as waste heat, but in cogeneration this thermal energy is put to good use.

Overview

Thermal power plants (including those that use fissile elements or burn coal, petroleum, or natural gas), and heat engines in general, do not convert all of their thermal energy into electricity. In most heat engines, a bit more than half is lost as excess heat (see: Second law of thermodynamics and Carnot's theorem). By capturing the excess heat, CHP uses heat that would be wasted in a conventional power plant, potentially reaching an efficiency of up to 80%,^[8] for the best conventional plants. This means that less fuel needs to be consumed to produce the same amount of useful energy.

Steam turbines for cogeneration are designed for extraction of steam at lower pressures after it has passed through a number of turbine stages, or they may be designed for final exhaust at back pressure (non-condensing), or both.^[9] A typical power generation turbine in a paper mill may have extraction pressures of 160 psig (1.103 MPa) and 60 psig (0.41 MPa). A typical back pressure may be 60 psig (0.41 MPa). In practice these pressures are custom designed for each facility. The extracted or exhaust steam is used for process heating, such as drying paper, evaporation, heat for chemical reactions or distillation. Steam at ordinary process heating conditions still has a considerable amount of enthalpy that could be used for power generation, so cogeneration has lost opportunity cost. Conversely, simply generating steam at process pressure instead of high enough pressure to generate power at the top end also has lost opportunity cost. (See: Steam turbine#Steam supply and exhaust conditions) The capital and operating cost of high pressure boilers, turbines and generators are substantial, and this equipment is normally operated continuously, which usually limits self generated power to large scale operations.

Some tri-cycle plants have used a combined cycle in which several thermodynamic cycles produced electricity, then a heating system was used as acondenser of the power plant's bottoming cycle. For example, the RU-25 MHD generator in Moscow heated a boiler for a conventional steam powerplant, whose condensate was then used for space heat. A more modern system might use a gas turbine powered by natural gas, whose exhaust powers a steam plant, whose condensate provides heat. Tri-cycle plants can have thermal efficiencies above 80%.

The viability of CHP (sometimes termed utilisation factor), especially in smaller CHP installations, depends on a good baseload of operation, both in terms of an on-site (or near site) electrical demand and heat demand. In practice, an exact match between the heat and electricity needs rarely exists. A CHP plant can either meet the need for heat (heat driven operation) or be run as a power plant with some use of its waste heat, the latter being less advantageous in terms of its utilisation factor and thus its overall efficiency. The viability can be greatly increased where opportunities for Trigenerationexist. In such cases, the heat from the CHP plant is also used as a primary energy source to deliver cooling by means of an absorption chiller.

CHP is most efficient when heat can be used on-site or very close to it. Overall efficiency is reduced when the heat must be transported over longer distances. This requires heavily insulated pipes, which are expensive and inefficient; whereas electricity can be transmitted along a comparatively simple wire, and over much longer distances for the same energy loss.

A car engine becomes a CHP plant in winter when the reject heat is useful for warming the interior of the vehicle. The example illustrates the point that deployment of CHP depends on heat uses in the vicinity of the heat engine.

Cogeneration plants are commonly found in district heating systems of cities, hospitals, prisons, oil refineries, paper mills, wastewater treatment plants, thermal enhanced oil recovery wells and industrial plants with large heating needs.

Thermally enhanced oil recovery (TEOR) plants often produce a substantial amount of excess electricity. After generating electricity, these plants pump leftover steam into heavy oil wells so that the oil will flow more easily, increasing production. TEOR cogeneration plants in Kern County, California produce so much electricity that it cannot all be used locally and is transmitted to Los Angeles^{[citation needed]}.

CHP is one of the most cost-efficient methods of reducing carbon emissions from heating systems in cold climates.

Utility pressures versus self generating industrial

Industrial cogeneration plants normally operate at much lower boiler pressures than utilities. Among the reasons are: 1) Cogeneration plants face possible contamination of returned condensate. Because boiler feed water from cogeneration plants has much lower return rates than 100% condensing power plants, industries usually have to treat proportionately more boiler make up water. Boiler feed water must be completely oxygen free and de-mineralized, and the higher the pressure the more critical the level of purity of the feed water.^[9] 2) Utilities are typically larger scale power than industry, which helps offset the higher capital costs of high pressure. 3) Utilities are less likely to have sharp load swings than industrial operations, which deal with shutting down or starting up units that may represent a significant percent of either steam or power demand.

Comparison with a heat pump

A heat pump may be compared with a CHP unit, in that for a condensing steam plant, as it switches to produced heat, then electrical power is lost or becomes unavailable, just as the power used in a heat pump becomes unavailable. Typically for every unit of power lost, then about 6 units of heat are made available at about 90°C. Thus CHP has an effective COP compared to a heat pump of 6.^[11] It is noteworthy that the unit for the CHP is lost at the high voltage network and therefore incurs no losses, whereas the heat pump unit is lost at the low voltage part of the network and incurs on average a 6% loss. Because the losses are proportional to the square of the current, during peak periods losses are much higher than this and it is likely that widespread i.e. city wide application of heat pumps would cause overloading of the distribution and transmission grids unless they are substantially reinforced.

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ORGANIC RANKINE CYCLE POWER PLANT FOR WASTE HEAT RECOVERY

                                          ORGANIC RANKINE CYCLE POWER PLANT
                                                  FOR WASTE HEAT RECOVERY



Keywords:  Organic Rankine Cycle, Waste Heat Recovery, Cement Industry, Gas Compression
Station
ABSTRACT
Power Plants based on the Organic Rankine Cycle (ORC) have been increasingly employed over the last 20
years to produce power from various heat sources when other alternatives were either technically not practical
or not economical. These power plants in sizes from 300 kW to 130 MW have demonstrated the maturity of this
technology. The cycle is well adapted to low moderate temperature heat sources such as waste heat from
industrial plants and is widely used producing 600 MW of electric power from geothermal and waste heat
resources. The ORC technology is applicable to heat recovery of medium size gas turbines and cement plants,
and o ers significant advantages over conventional steam bottoming cycles. One such system, the 6.5 MW Gold
Creek Power Plant is now in operation at a gas compressor station in Canada displacing some 25,000 tons of
CO2 yearly. The Gold Creek Power Plant is owned and operted by a subsidiary of Transcanada Pipeline. A
second system of 1.5 MW is operating at the Heidelberger Zement AG Plant in Lengurt, Germany. These
environmentally friendly power plants are the first to be installed in these industries. The Cement power plant is
recovering unused grate cooler heat and is generating electricity on a continuosly basis without interfering with
the initial clinker production process, displacing some 7000 t of CO2 yearly. The use of ORC technology based
systems has matured to a field proven and highly reliable technology. ORC have demonstrated advantages over
conventional steam cycles and are particularly applicable to geothermal power plants and the recovery of waste
heat, from small to medium gas turbines such as the compressor stations, while providing cost and
environmental advantages.



1. INTRODUCTION
A. Lengfurt Cement Power Plant
The ORMAT    heat recovery system at the Heidelberger Zement AG Plant in Lengfurt is the first of such
systems supplied to the cement industry. (Figure 1) This environmentally friendly plant recovers the unused
grate cooler heat and generates 1,300 kW of electricity on a continuous basis, amounting to over 10% of the
cement plant's internal electricity use, without interfering with the initial clinker production process. The waste
heat recovery power plant will result in the saving of 7,000 tons of CO2 annually.
Even for an optimized cement process, significant heat loss, mainly caused by the heat of the waste gases, still
occurs. The heat balance of a kiln plant reveals that preheater waste gases and cooler exhaust air account for
more than 30% of that heat loss.
Waste heat sources may be directly used for drying of raw material, coal or intergrinding matter. However, there
are numerous cement plants where this utilization is either not possible or not required and this unused heat is
lost. The economic order of magnitude of such losses in a typical kiln line of 2000 t/d capacity with a 4-stage
cyclone preheater and grate cooler, is as follows: Assuming a preheater waste-gas temperature of 350°C and grate cooler exhaust-air temperature of 275°C,
approximately 1,100 kJ/kg (clinker) of unused heat is lost. When firing coal of a net calorific value of 23,000
kJ/kg, the annual loss to be attributed to unused process heat is approximately US $1.0 – $1.6 million; a very
significant expense for lost energy.
The preferred approach to overcome this economically unsatisfactory situation is to use the waste heat for the
generation of electrical power. In the past some cement plant operators have installed waste heat steam boilers
in their plants and have utilized the process heat to operate a steam turbine generator set. However, the
conventional steam technology has certain implicit drawbacks with respect to the cement production process. In
particular, the use of the relatively low temperature grate-cooler exhaust air, available at continuously varying
temperatures, ranging from 170°C to 300°C, involves difficulties with respect to stable steam turbine operation
due to the high moisture content in the turbine exhaust and pinch point interference problems in the boiler. To
overcome this drawback, exhaust air temperatures have been raised, in some cases beyond the level required for
clinker burning, through additional fuel gas firing. This has increased the fuel consumption in the plant to
unacceptable levels.







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Machine design basic concepts

The inaugural issue of Machine Design coincided almost exactly with the 1929 stock-market crash and the beginning of the Great Depression. Although the nation was in the economic doldrums, there was significant design development taking place in almost all industrial segments including automotive, aircraft, farm equipment, home appliances, and industrial machinery.

The onset of World War II saw the close of the Great Depression and brought almost frenetic activity to design engineering at large. After the war, civilian industries thrived. But in the years following the war and into the 1950s the role of design engineer languished, stigmatized by the war effort as the creator of new means of destruction.

Engineering colleges began to feel slighted because doctors, lawyers, and business executives were viewed as having more prestige and professional status than their engineering graduates.^[1]Intellectual elites viewed engineering colleges as trade schools, and graduate engineers were said to be nothing more than mechanics or glorified shop hands. In response, engineering schools began to drop courses that lacked academic rigor or had the slightest blue-collar aura.

The launch of Sputnik in 1957 again changed the perception of design engineering. The perceived loss of world leadership in air and space technology by the people of the United States set the stage for a considerable renewal of prestige to the engineering discipline. After more than a decade into the Cold War, the public realized science and engineering could play a key role in keeping the Communists at bay. The government unloaded almost limitless supplies of money on high-tech defense industries, and engineering became the career of choice. High salaries and generous perks were lavished on engineers and scientists.

Unfortunately, Sputnik also accelerated the movement to delete courses on manufacturing and shop practice from the curricula of top schools. The idea was to portray engineers as being more scientist than mechanic. The rocket scientist working on the space program became the image to which most engineers aspired.

This attitude had a lot to do with framing the editorial policies of Machine Design through the 1960s. The policies were in tune with what was happening in the largest and most-sophisticated corporations, especially the aircraft and automotive industries, where design engineering and manufacturing engineering were increasingly treated as separate entities having no common interest. Reflecting this, articles selected for Machine Design were carefully tailored not to have too much of a manufacturing orientation.

Starting in the late 1960s, another shift in American perception was brought about by the growing awareness of overseas manufacturing facilities returning a lower cost product with higher quality. While lower labor rates played a key role in the lower costs, they could not justify the higher reliability of offshore products over those domestically produced. It was soon dsicovered that those shops with higher quality production realized design and manufacturing engineering were closely intertwined. Machine Design articles started to reflect this trend. For example, it's believed to be the first industrial trade magazine to run a comprehensive article explaining numerical control machining and how it relates to design engineering.

Machine Design's coverage of manufacturing positioned it well when concurrent engineering became the trendy idea in industry. Major corporations suddenly discovered that design and manufacturing were interrelated, and it became vogue to tear down the walls between design and manufacturing engineers.

In the 1970s, finite-element analysis broke on the industrial scene. Computer-aided design was evolving, and by the 1980s, it was also having a profound impact on design procedures. Computer-aided manufacturing evolved separately, but by 1990 CAD and CAM had merged. In the field of electrical and electronic technology, relay controls were giving way to digital electronics and themicroprocessor that led to combining a number of design disciplines into the technologies of mechatronics and motion control.

For over 80 years, Machine Design had predicted and led the industrial community spotting trends and fundamental changes in manufacturing operations. Providing an ongoing series of technological overviews interspersed with in-depth tutorials, it kept readers abreast of technologies that were transforming product design. It does this with an editorial staff of degreed engineers possessing industrial experience and obligated to create lucid and interesting articles supported by the intelligent use of graphics.

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A book of R. S. Khurmi.........

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Applied Calculus

Applied Calculus for Business, Economics, and the Social and Life Sciences, Expanded Edition 

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