Reciprocating engine – wikipedia electricity for refrigeration heating and air conditioning 9th edition pdf


There may be one or more pistons. Each piston is inside a cylinder, into which a gas is introduced, either already under pressure (e.g. steam gas tax engine), or heated inside the cylinder either by ignition of a fuel air mixture ( internal combustion engine) or by contact with a hot heat exchanger in the cylinder ( Stirling engine). The hot gases expand, pushing the piston to the bottom of the cylinder. This position is also known as the Bottom Dead Center (BDC), or where the piston forms the largest volume in the cylinder. The piston is returned to the cylinder top ( Top Dead Centre) (TDC) by a flywheel, the power from other pistons connected to the same shaft or (in a double acting cylinder) by the same process acting on the other side of the piston. This is where the piston forms the smallest volume in the cylinder. In most types the expanded or exhausted gases are removed from the cylinder by this stroke. The exception is the Stirling engine, which repeatedly heats and cools the same sealed quantity of gas. The stroke is simply the distance between the TDC and the BDC, or the greatest distance that the piston can travel in one direction.

In most types, the linear movement of the piston is converted to a rotating movement via a connecting rod and a crankshaft or by a swashplate or other suitable mechanism. A flywheel is often used to ensure smooth rotation or to store energy to carry the engine through an un-powered power generation definition part of the cycle. The more cylinders a reciprocating engine has, generally, the more vibration-free (smoothly) it can operate. The power of a reciprocating engine is proportional to the volume of the combined pistons’ displacement.

A seal must be made between the sliding piston and the walls of the cylinder so that the high pressure gas above the piston does not leak past it and reduce the efficiency of the engine. This seal is usually provided by one or more piston rings. These are rings made of a hard metal, and are sprung into a circular groove in the piston head. The rings fit closely in the gas mask art groove and press lightly against the cylinder wall to form a seal, and more heavily when higher combustion pressure moves around to their inner surfaces.

It is common to classify such engines by the number and alignment of cylinders and total volume of displacement of gas by the pistons moving in the cylinders usually measured in cubic centimetres (cm³ or cc) or litres (l) or (L) (US: liter). For example, for internal combustion engines, single and two-cylinder designs are common in smaller vehicles such as motorcycles, while automobiles typically have between four and eight, and locomotives, and ships may have a dozen cylinders or more. Cylinder capacities may range from 10 cm³ or less in model engines up to thousands of liters in ships’ engines. [2]

The bore/stroke ratio is the ratio of the diameter of the piston, or bore, to the length of travel within the cylinder, or stroke. If this is around 1 the engine is said to be square, if it is greater than 1, i.e. the bore is larger than the stroke electricity and circuits class 6 pdf, it is oversquare. If it is less than 1, i.e. the stroke is larger than the bore, it is undersquare.

Cylinders may be aligned in line, in a V configuration, horizontally opposite each other, or radially around the crankshaft. Opposed-piston engines put two pistons working at opposite ends of the same cylinder and this has been extended into triangular arrangements such as the Napier Deltic. Some designs have set the cylinders in motion around the shaft, such as the Rotary engine.

In steam engines and internal combustion engines, valves are required to allow the entry and exit of gases at the correct times in the piston’s cycle. These are worked by cams, eccentrics or cranks driven by the shaft of the engine. Early gas in california designs used the D slide valve but this has been largely superseded by Piston valve or Poppet valve designs. In steam engines the point in the piston cycle at which the steam inlet valve closes is called the cutoff and this can often be controlled to adjust the torque supplied by the engine and improve efficiency. In some steam engines, the action of the valves can be replaced by an oscillating cylinder.

Aside from looking at the power that the engine can produce, the Mean Effective Pressure (MEP), can also be used in comparing the power output and performance of reciprocating engines of the same size. The mean effective pressure is the fictitious pressure which would produce the same amount of net work that was produced during the power stroke cycle gas efficient cars 2012. This is shown by:

An early known example of rotary to reciprocating motion is the crank mechanism. The earliest hand-operated cranks appeared in China during the Han Dynasty (202 BC–220 AD). [3] Several saw mills in Roman Asia and Byzantine Syria during the 3rd–6th centuries AD had a crank and connecting rod mechanism which converted the rotary motion of a water wheel into the linear movement of saw blades. [4] In 1206, Arab engineer Al-Jazari invented a crankshaft. [5]

The reciprocating engine developed in Europe during the 18th century, first as the atmospheric engine then later as the steam engine. These were followed by the Stirling engine and internal combustion engine in the 19th century. Today the most common form gas finder of reciprocating engine is the internal combustion engine running on the combustion of petrol, diesel, Liquefied petroleum gas (LPG) or compressed natural gas (CNG) and used to power motor vehicles and engine power plants.

One notable reciprocating engine from the World War II Era was the 28-cylinder, 3,500 hp (2,600 kW) Pratt Whitney R-4360 Wasp Major radial engine. It powered the last generation of large piston-engined planes before jet engines and turboprops took over from 1944 onward. It had a total engine capacity of 71.5 L (4,360 cu in), and a high power-to-weight ratio.

The largest reciprocating engine in production at present, but not the largest ever built, is the Wärtsilä-Sulzer RTA96-C turbocharged two-stroke diesel engine of 2006 built by Wärtsilä. It is used to power the largest modern container ships such as the Emma Mærsk. It is five stories high (13.5 m or 44 ft), 27 m (89 ft) long, and weighs over 2,300 metric tons (2,500 short tons) in its largest 14 cylinders electricity video ks1 version producing more than 84.42 MW (114,800 bhp). Each cylinder has a capacity of 1,820 L (64 cu ft), making a total capacity of 25,480 L (900 cu ft) for the largest versions.

For piston engines, an engine’s capacity is the engine displacement, in other words the volume swept by all the pistons of an engine in a single movement. It is generally measured in litres (l) or cubic inches (c.i.d., cu in, or in³) for larger engines, and cubic centimetres (abbreviated cc) for smaller engines. All else being equal, engines with greater capacities are more powerful and consumption of fuel increases accordingly (although this is not true of every Reciprocating engine), although power and fuel consumption are affected by many factors outside of engine displacement.

Reciprocating engines can gas key staking tool be characterized by their specific power, which is typically given in kilowatts per litre of engine displacement (in the U.S. also horsepower per cubic inch). The result offers an approximation of the peak power output of an engine. This is not to be confused with fuel efficiency, since high efficiency often requires a lean fuel-air ratio, and thus lower power density. A modern high-performance car engine makes in excess of 75 kW/L (1.65 hp/in 3).