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Stirling engine

Description:

A Stirling motor is a heat engine that operates by cyclic compression and expansion of air or other gas, the working fluid, at different temperature levels such that there is a net conversion of heat energy to mechanical work. The motor is an external combustion unit like a steam engine in that all heat transfer takes place through the engine wall and the heat source is outside the engine. But unlike the steam engine, the working fluid used by the Stirling motor is a fixed quantity of gas either air or other type. Similarly to other heat engines, the general cycle consists of compressing cool gas, heating the gas, expanding the hot gas, and finally cooling the gas again before repeating the cycle. The Stirling motor is noted for its high efficiency, quiet operation, and can be used with any type of heat source as the renewable ones.

The Stirling Motor unit designed by PEZHVAK PAZHOOH SANAT is an alfa type engine. It consists of two power pistons located in separate cylinders (one for the cold source and another for the hot one). They are connected to a tube where the regenerator is located, which stores and transfer the heat, that enables to reach a higher efficiency. There is a piston in each cylinder, they move with a phase difference of 90º between them. Cylinders are connected by a crankshaft, which makes the power/volume ratio be quite high, since the power transfer mechanism is very simple. Gas moves between the both cylinders in a close circuit. The external heat source provides energy to the hot cylinder and the expansion of the gas moves its piston, which is fixed to the other piston of the cold cylinder by means of a crankshaft. The hot gas passes to the cold cylinder. During this time the cold cylinder piston compresses the cooled gas and forces it to move to the hot cylinder, where it receives the heat from the hot source and the cycle starts again.

Experimental and practical Possibilities:

Study of the conversion of thermal-mechanical-electrical energy

Study of the relationship between the temperatures difference of the thermal machine and the speed generated.

 Calculation of the "threshold" temperatures difference which generates motion

Study of the mechanical and electrical power in relation to speed

Mechanical an electrical efficiency calculation

Device component:

Alpha type stirling engine

Heater

Pulley

Generator

Pressure and temperature sensor

Diesel engine

Description:

The engine used here is a single-cylinder diesel engine. It has its own closed cooling water circuit. A solid welded frame on rollers, with a vibration insulated base plate, carries the entire set-up. Hazardous areas such as hot surfaces and rotating parts are covered with perforated plates. The connection to the brake is made via a rotationally elastic coupling with a jointed shaft. The engine is attached to the load unit by fasteners. The engine is fitted with sensors that measure the temperatures and the cooling water flow rate. The switch cabinet contains all of the electronic equipment for managing the engine (factory set). On the switch cabinet are an ignition key, an operating time counter and warning lamps. Data is transferred between load unit and the engine via a data cable connecting the switch cabinets for the two units. For safety reasons, the engine has been modified in a way that it only starts when it is connected to the load unit both mechanically and electrically. The well-structured instructional material sets out the fundamentals and provides a step-by-step guide through the experiments.

Learning Objective:

Plotting torque and power curves

Determination of specific fuel consumption

Determination of volumetric efficiency and lambda (fuel-air ratio)

Overall engine efficiency

Device component:

Single –cylinder diesel engine

Fuel tank

Dynamometer

Thermocouple

Orifice for air flow measuring

Digital panel

Gasoline engine

Description:

The engine used here is a Single-cylinder petrol engine with a controlled catalytic converter. It has its own closed cooling water circuit. A solid welded frame on rollers, with a vibration insulated base plate, carries the entire set-up. Hazardous areas such as hot surfaces and rotating parts are covered with perforated plates. The connection to the brake is made via a rotationally elastic coupling with a jointed shaft. The engine is attached to the load unit by fasteners. The engine is fitted with sensors that measure the temperatures and the cooling water flow rate. The switch cabinet contains all of the electronic equipment for managing the engine (factory set). On the switch cabinet are an ignition key, an operating time counter and warning lamps. Data is transferred between the load unit and the engine via a data cable connecting the switch cabinets for the two units. A starter battery is also housed in the frame. For safety reasons, the engine has been modified in a way that it only starts when it is connected to the load unit both mechanically and electrically. The well-structured instructional material sets out the fundamentals and provides a step-by-step guide through the experiments.

Learning Objective:

Single-cylinder internal combustion engine function

Torque and power curve

Exhaust temperature curve

Calculate specific fuel consumption

Thermal efficiency

Device component:

Single –cylinder gasoline engine

Fuel tank

Dynamometer

Thermocouple

Orifice for air flow measuring

Digital panel