Valve regulators in refrigeration systems
Valves perform a variety of functions in refrigeration systems. They are used for expansion of vapour, regulating flow of water or vapour, pressure and temperature regulation, activating a device, oil level control etc. Depending on the function there are various types of valves available viz. expansion valves, stop & regulating valves, solenoid valves, safety valves, pressure controlled valves, etc.
Valve regulators are used for many different functions in commercial and industrial refrigeration like capacity regulation, condensing pressure regulation, evaporation pressure regulation, receiver pressure regulation, crankcase pressure regulation etc.
Capacity valve regulators adjust compressor capacity to actual evaporator load in applications like air driers and water chillers where the evaporating temperature is around 0 deg C. They maintain compressor suction pressure by injecting hot / cool gas from the higher pressure side. When pressure drops at the outlet these valve regulators open up to achieve pressure regulation.
They are hermetically sealed and made of bimetal as well as stainless steel.
Spacecraft. A Vehicle designed for Spaceflight
A vehicle designed for spaceflight is called a spacecraft. When the spacecraft travels on a sub-orbital flight, the vehicle travels to the outer-space and returns to Earth without taking a full orbit.
On the other hand, a spacecraft taking an orbital space flight completes the orbiting of the Earth before returning to the planetary surface.
Spacecrafts may be of two types, one that carries people as its crews or passengers, and the other is the robotic spacecraft which is controlled by either autonomously or tele-robotically.
The use of robotic spacecrafts are of two types, the one which leaves just vicinity of the Earth are called space probes, and the other which remain in orbit of the Earth are called artificial satellites.
There are quite a few uses of spacecraft that goes into the outer space. They are used for several purposes, which would include communication, meteorological assessments, warfare, navigation, planetary exploration, and many more.
Depending upon the purpose for which a spacecraft has been built, the vehicle may consist of several sub-systems, which are applicable to the mission profile of the spacecraft. Few of the important sub-assemblies are briefly discussed below.
Automobile Engines
The working of an automobile engine follows the same principle as an internal combustion engine. Air, from outside, enters the engine through the air cleaner and reaches the throttle plate.
The pedal in your car is the control for the amount of air that you would want to be taken in, and you control it by pressing on this gas pedal.
The air is then distributed through the intake manifold of the cylinders.
At some point fuel is injected into the air stream, and the mixture vaporizes and is drawn into the cylinders as they start their intake stroke.
This way, when the cylinder has reached its bottom, it has drawn in sufficient mixture. As it moves up, compressing the mixture, the spark plug ignites the mixture, and as the powerful gas formed expands, it pushes the cylinder to the bottom with the cylinder once again drawing in the mixture.
In designing automobile engines, you need to be a specialist in automobile engineering.
The consideration that is taken while designing such an engine is whether it should be a carburetor or a diesel one. carburetor engines are most commonly found in passenger cars and low capacity trucks, while trucks with a capacity over two tons are fitted with diesel engines, including dump trucks, trailer tractors and bus.
Increasingly the medium and low-capacity vehicles are being fitted with diesel engines, since the fuel consumption of these engines are 30% to 50% lower than the carburetor engines.
Diesel engines not only cost more, but maintenance is much more expensive than the other type of engine. Diesels require more metal parts per kilowatt.
The critical parts of diesel engines are made of alloy steel, and the fuel injection system is much more expensive than carburetor engines.
How to make a career in Automotive Engineering
To make a career in automotive engineering, there are several engineering technology programs that are offered as various academic courses helping you to specialize in designing vehicles, such as, cars, trucks, etc.
You gather the expertise in providing help to build and test the vehicles, and learn how to repair and maintain with the appropriate tools and instruments. When you watch TV, you come across commercials advertising cars and other vehicles.
If you ponder for once how much it costs the vehicle manufacturers to advertise, you would be able to realise how vast the automobile industry is. If you watch the commercials closely, you will find that features of the vehicle are advertised also, such as, side air-bags, disappearing fold down seats, gas-electric hybrids, and many more.
It is evident that someone had to design these features which are now being made available in the vehicle.
When designing a vehicle, the design break-through comes from the automobile engineers, who have the specialization to design automobiles.
The job that you have as an automobile design engineer is to design the components that go into the vehicle, test them in the laboratory, and qualify them as the components which have been correctly designed. Automobile design engineers put the concept of a vehicle into reality.
The making of an Automobile
The products manufactured by the automotive industry are the passenger cars, trucks, vans, sport concerned vehicles, busses, and recreational vehicles.
The industry is one of the largest industry in the US and employees over 2 million people.
Automotive industries are mostly concentrated in the Great Lakes area, especially in Michigan, but it can be found in most of the other parts of the country as well.
Employment opportunities in the industry offers tens and thousands of job to the higher skilled personnel, such as, highly educated scientists, engineers, managers, and other professionals. It also has large openings for thousands of skilled workers, who largely work in the production line, and unskilled laborers.
Generally, each of the automobile manufacturers bring out new line of vehicles every year, the planning and design of which start at least two to three years earlier before you find it in a dealer’s showroom. Before these new line of vehicles are brought out, the planning stage of these new models are first considered by the company’s highest officials, along with their product planning group.
Here the broad outline of the vehicles are decided, deciding on matters, such as, whether to emphasize on luxury models or to consider such matters as to keep the price low. The aspects on safety measures, fuel economy, the size, the weight, and air pollution control are also considered and decided.
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