When the charge enters from both side intake ports, the charge flows upwards and after the combustion, the burnt gases go out of the cylinder from the exhaust valve which is located at the top of the cylinder. Less air loss occurs and has lower fuel consumption hence gives better efficiency as compared to other methods.
The good scavenging obtains during the low speed and the high speed using uniflow scavenging method. The uniflow scavenging commonly is used in large-sized two strokes engines such as in two-stroke ic engines of big marine ships. The cross-flow type scavenging has an inlet port and the exhaust port that are located on the opposite sides to each other. The deflector piston hump-shaped piston head is used in this type of scavenging. When the charge enters into the engine from the intake port, due to the hump shape of a piston, this incoming charge moves upwards and pushes the upper burnt gases to the downside and then these gases goes outwards through the exhaust port.
This method of scavenging performs well during the low speed of the engine while bad scavenging obtains at the high speed of the engine or at full throttle time. If filter C is blocked the device G can still be operated by direct circuit through pressure switch F and valve E. Fig 6. It continues till the piston reaches its bottom dead center BDC. This completes one revolution of the crank shaft. At this moment, temperature of the compressed air is sufficiently high to ignite the fuel.
It suddenly increases the pressure and temperature of the products of combustion. The fuel oil is continuously injected for a fraction of the revolution.
The piston is pushed downwards with a great force the hot burnt gases expand giving high speed to the piston. During this expansion, some of the heat energy is transformed into mechanical work.
This movement of the piston pushes out of the products of combustion from the engine cylinder through the exhaust valve into the atmosphere. This completes the cycle and the engine cylinder is ready to suck the fresh air once again. By rotating the flywheel in clockwise direction, note down the angular position of the Flywheel and fill up the observation table and draw the valve timing diagram.
Injection continues till IC — IS this period……………………….. CR max - 4. The head replaces original engine head.
An additional reverted piston and cylinder assembly is provided to vary clearance volume. A jacket cooling system is provided to cool this head with the water. Always ensure adequate water flow while running engine. An index holes are provided it can act as locking also by inserting a spring loaded pin into the hole. Rise in level is indicated and calibrated in terms of CR. A special spark plug replaces original is also used.
Original Values of Compression ratio CR. Check all electrical connection. Ensure water level in manometer. Ensure oil level in engine. Tighten all fuel lines. Open valve of 3 way blocks, make fuel flow to engine directly.
Now allow water into chamber auxiliary cylinder for cooling. Either rotates clockwise or counterclockwise to adjust compression ratio. Initially set the Compression Ratio to its maximum value. With the help of rope start the engine. Wait until it stabilizes for rated speed. Now take readings of manometer.
Method of manometer reading. Close valve of 3-way block, now fuel flows to engine from burette. Note down time taken for 10 cc of fuel. Note down spring balance reading along with others. Repeat experiment for different load. Observe that at lower CR speed drops and also efficiency. It is marked with 5-mm scale.
Spring Balances : 2 nos. Manometer : U rube, 30 cm, water filled b. Air Tank : 30 x 30 x 30 cm with diaphragm c. Orifice : Circular. Main Fuel tank - with bottom shutoff ball valve b. Burrette, cc. Fill up sufficient diesel in diesel tank. Check oil level in the engine. It should be up to the top edge of the flat portion provided over the oil dipstick.
If oil level is reduced, add up clean SAE oil to the crank case by opening the valve cover at the top of the engine. Replace the cover after filling the oil. Fill up water in manometer up to half of the manometer height. Start the water supply and see that water is flowing through engine jacket, brake drum and exhaust gas calorimeter. Put off the water in the brake drum. If diesel tank was empty before filling the diesel, remove air bubbles in fuel pipe, by opening the vent screw provided at the right side, top of the fuel pump.
Release the loading screw so that there is no tension in the rope. Lift up decompression lever, at the side of the valve cover.
Put the handle over the starting shaft and rotate the shaft. As engine picks up sufficient speed, drop the decompression lever. The engine will start. Remove the handle immediately. As engine picks up speed, start water to the brake drum. Load the engine with loading screw, and set the spring balance difference to, say 2Kgs.
Open burette filling cock, take sufficient diesel in burette and close the cock. Note down brake drum speed with tachometer tachometer is not supplied along with the unit and manometer difference. Note down jacket cooling water and calorimeter water flow rates. Note down temperatures from the channels 1 to 5. Repeat the steps 9 to 14 for different loads, say 4 Kg, 6-Kg etc, and complete the observation table. Manometer diff, hw, cm.
Time for 1 lit calorimeter water, tc, sec. Time for 1 lit jacket water tj, sec. Water inlet temp. T1 Water outlet from calorimeter temp. T2 Water outlet from engine jacket temp. T3 Exhaust gas outlet from engine before Calorimeter temp.
T4 Exhaust gas outlet from calorimeter temp. BP for different readings. Extend the line to meet zero FC. The power on negative side at which FC is zero is friction power, FP. Debit side consists of following parameters i Heat equivalent to BP ii Heat carried away by jacket cooling water. Cpeg x T4 — T1 iv Heat loss by radiation and unaccounted losses, is taken as difference. What are the differences between the Diesel and Petrol engine? List the name of the components especially available in Diesel engine only.
What is the working principle of thermocouple? And name the type of thermocouple used here. Put sufficient petrol in petrol tank. Check oil level in engine with the help of dipstick provided. Ensure water supply through jacket and exhaust gas calorimeter. Insert the key in the ignition switch and start the engine. Keep engine speed at certain desired value, say rpm. Adjust the engine speed again to previous value.
Keep the pointer on dynamometer arm below the dial gauge in line with stationary arrow by a hand wheel provided above the dial gauge. Note down various observations like load on dial gauge, fuel consumption etc. Repeat the procedure at different loads, keeping engine speed constant. Morse Test - Keep certain load on the engine at same speed. Note down the load indicated.
Do not disturb accelerator position. Don't put off more than one switch at a time. Only one switch is to be put off at a time. Repeat the procedure at different speeds.
Release the entire load. Increase the load. Do not disturb the accelerator position. Again note down the observations. Repeat the procedure at different accelerator position. Machine tools are those machines that make machines and products for industrial purposes. The intention of the modern industry is to create a number of useful….
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In the last session, we had discussed Vapor Compression Refrigeration Cycle and in today's session, we can discuss in detail the…. Topics of Today. Reciprocating Engine. Rotary Engine. Otto Cycle Diagram. Diesel Cycle Diagram. Four-Stroke Engine.
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