Test Rig for a 4 Stroke Diesel Engine

1.     INTRODUCTION

         We are making a test rig for the 4 stroke single cylinder water cooled diesel engine. This engine is produced by KAMCO AGRO MACHINERY. Through this test rig, we will be able to test the parameters like performance and heat balance of this engine.

          The construction of any test rig is a very difficult job. In the case of a 4 stroke water cooled diesel engine, it becomes more difficult. It was a toughest task to complete this project. The test rig is consisting of a brake drum which is loaded gradually with a couple of spring balances connected to it. Engine to be tested, brake drum, spring balances, manometer, etc. are the main components f the test rig.

Fig.1 Kamco engine fitted in a tiller

COMPONENTS OF THE TEST RIG

1. ENGINE TO BE TESTED

2. SPRING BALANCE

3. BRAKE DRUM

4. PANEL BOARD

2.    ENGINE TO BE TESTED

The engine employed in this test rig is the KAMCO ER90 Engine equipped with Radiator and specially designed die cast multi blade axial fan. The engine can be operated continuously for several hours. It can be used as prime mover either for stationary or for moving applications.

Main components of this engine are

2.1 THE CYLINDER BLOCK

The cylinder block is the most important and heavy component of an engine as it forms the core of the engine. A very heavy, intricate and cast iron (increasingly aluminum) block made to incorporate all those numerous other parts that make up the mystery of automobile power house. The cylinder block houses the engine cylinders, which serve as the bearings or guides for the pistons reciprocating within them. Around the cylinders there are passages for the circulation of coolant. The circulation of this coolant is perhaps a very critical function since the amount of heat generated while the engine is functioning is enough to melt the engine itself, if it were for the coolant taking all the heat away

The cylinder block has not just the minute holes for the coolant to pass through, but it also has holes for lubricating oil to pass through. Lubrication is needed for he machine parts to work seamlessly and not let friction seize the proper functioning of the cylinder.

Fig.2 Cylinder block

2.2 CYLINDER HEAD

In an external combustion engine, the cylinder head (often informally abbreviated to just head) sits above the cylinders on op of the cylinder block. It consists of a platform containing part of the combustion chamber, and the location of the poppet valves and spark plugs and the head is essentially a flat plate of metal bolted to the top of the cylinder bank with the head gasket in between them. This design, however, requires the incoming air to flow through a convoluted path, which limits the ability of the engine to perform at higher revolutions per minute (rpm), leading to the adoption of the overhead valve (ohv) head design, and the subsequent overhead camshaft (ohc) design.

2.3 PISTONS

Most common engines have 4, 6, or 8 pistons which move up and down in the cylinders. On the upper side of the piston is what is called the combustion chamber where the fuel and air mix before ignited. On the other side is he crank case which is full of oil. Pistons have rings which serve to keep the oil out of the combustion chamber and the fuel air out of the oil.

2.4 VALVES

The intake and exhaust valves open at the proper time to let in air and fuel and to let out exhaust. Both valves are closed during compression and combustion strokes so that the combustion chamber is sealed.

2.5 PISTON RINGS

Piston Rings provide a sliding seal between the outer edge of the piston and the inner edge of the cylinder.

The rings serve two purposes:

1.      They prevent the fuel/air mixture and exhaust in the combustion chamber from leaking into the sump during compression and combustion

2.      They keep oil in the sump from leaking into the combustion area, where it would be burned and lost.

Most cars that “burn oil” and have a quart added every 1000 miles are burning it because the engine is old and the rings no longer seal things properly.

2.6 CONNECTING ROD

The connecting rod connects the piston to the crankshaft. It can be rotated at both ends so that its angle can be hanged as the piston moves and thus the crank shaft rotates.

2.7 CRANK SHAFT

The crank shaft is connected to the pistons via a connecting rod. As the piston moves up and down in the cylinder, it rotates the crank shaft and converts the straight line motion into rotary motion.

2.8 CAM SHAFT

A cam shaft is the shaft in the engine which has a series of cams for operating the valve mechanism. It is driven by gears or by sprockets and toothed belts or chain from the crank shaft.

Fig.3 engine head

The KAMCO diesel engine using for this experiment is fixed on a MS channel mounted on a concrete basement. A couple of MS channels are attached on the concrete basement with strong foundation bolts. Above them, engine placed very carefully. After the attaching of engine, we were engaged in the construction of rest of the instruments.

SPECIFICATIONS OF KAMCO ENGINE:

1. Model                                              : KMP 200 DI/DI 120 Super Engine     

2. Rated Horse Power             : 12 HP    

3. Engine Revolution              : 2000 RPM

4. Fuel Used                : Diesel

5. Diesel Consumption            : 720 to 750 ml/hr

6. Type of Engine                   : 4 Stroke, Singe Cylinder,

                                                            Horizontal, water cooled

7. Stroke Volume                    : 744 cc

8. Fuel Injection Pressure        : 250-258 kg/cm2

9. Valve Clearance                  : 0.3mm when engine is cooled

10. Cooling System                 : Pressure type Radiator – water cooling   

11. Fuel Tank Capacity           : 10.7 liters

12. Total Weight of Tiller       : 515 kg

13. Overall Length x Width x Height of Tiller: 240.5x95.5x113 cms

14. No. of Tilling Blades                    : 20 nos

15. Tilling Width                     : 60cms

16. Average Tilling Width     : 19 cms

17. Engine Lubricating Oil    : SAE 40 or equivalent (3 Liters)

18. Gear Box Oil                                 : SAE 90 or equivalent (5 Liters)

19. Chain Case                                    : SAE 40 or equivalent (1.5 Liters)

20. NUMBER OF SPEEDS: FORWARD 6, REVERSE 2 

3.    BRAKE DRUM

The brake drum is directly coupled to the engine flywheel. A canvas type belt is used to connect the brake drum with a couple of spring balances at their both ends. Loading the engine is made possible by rotating a hand wheel provided on the loading frame. This is a special application of brake drum to utilize in the loading of an engine. Brake drum is made of aluminum.

Fig.4  Brake Drum

The brake drum used in this test rig is loaded with rotating the hand wheels in the frame.

4.    SPRING BALANCE

Spring balance is the device used to measure the amount of load applied to the engine during the experiment in Kg

A spring balance is a part used mainly in mechanical timepieces. The balance spring, working together with the balance wheel, controls the speed of movement of the parts in the timepiece. The regulator lever is used to adjust the speed so that the timepiece keeps accurate time.

The invention of the balance spring in the 17th century greatly increased the accuracy of pocket watches and other timepieces by controlling the speed of movement of the mechanism to a nearly-constant rate. Improvements since then made timepieces even more accurate by reducing the effect of temperature, and also the effect of the driving force, which for a mainspring decreases as the mainspring winds down.

The balance spring is a fine spiral or helical spring used in mechanical watches, marine chronometers, and other timekeeping mechanisms to control the rate of oscillation of the balance wheel. A balance spring usually has a regulator lever to adjust the rate of the timepiece, but other designs use adjusting screws on the balance wheel instead. The balance spring is an integral part of the balance wheel, because it reverses the direction of the balance wheel so it oscillates back and forth. The balance spring and balance wheel together form a harmonic oscillator, whose resonant period is resistant to changes from perturbing forces, which is what makes it a good timekeeping device

4.1 MATERIALS USED IN SPRING BALANCE

A number of materials have been used for balance springs. Early on, steel was used, but without any hardening or tempering process applied; as a result, these springs would gradually weaken and the watch would start losing time. Some watchmakers, for example gold was used by John Arnold, which avoids the problem of corrosion, but retains the problem of gradual weakening. Hardened and tempered steel was first used by John Harrison and subsequently remained the material of choice until the 20th century.

In 1833, E. J. Dent (maker of the Great Clock of the Houses of Parliament) experimented with a glass Balance Spring. This was much less affected by heat than steel, reducing the Compensation required, and also didn't rust. Other trials with glass revealed that they were difficult and expensive to make, and there was a widespread opinion that they must be fragile. This latter objection is proved false by glass-fiber loft insulation and fiber-optic cables

Fig.6 Spring Balance

5.     PANEL BOARD

         It is very important to record the readings available during the experiment. We are using a panel board to fit the instruments required for the calculations. The panel board is used for fixing burette with 3 way lock and a U tube manometer. The 3 way lock of the burette is used to record the rate of fuel consumed during the test from the main fuel tank.

The instruments used in the panel board are,

         1. U tube monometer to measure quantity of air sucked into the cylinder.

2. Burette with manifold to measure the rate of fuel consumed during test.

 5.1 U TUBE MANOMETER 

        The simplest and useful pressure measure device consists of a transparent tube bent in the form of letter U and filled with a manometric liquid whose density is known.

The choice of a particular manometric liquid depends upon the pressure range and nature of the fluid whose pressure is sought. For high ranges, mercury (specific gravity 13.6) is the manometric/balancing liquid. For low pressure ranges, liquids like carbon tetrachloride (specific gravity 1.59) or acetylene tetrabromide (specific gravity 2.59) are employed. Quite often, some colors are added to the balancing liquid so as to get clear readings.

        A U tube manometer is a device used to find the difference in pressure between two points in a pipeline or in two different pipes or containers. In general, the U tube manometer fitted on the panel board, with a manometric liquid and with its ends connected to the points between which the pressure difference is to be measured. Fig.7 shows the typical U tube manometer

Fig.7 U Tube Manometer

5.2 BURETTE

        A burette (also known as buret) is a vertical cylindrical piece of laboratory glassware with a volumetric graduation on its full length and a precision tap, or stopcock, on the bottom. It is used to dispense known amounts of a liquid reagent in experiments for which such precision is necessary, such as a titration experiment. Burettes are extremely accurate - a 50 cm³ burette has a tolerance of 0.1 cm³ (class B) or 0.06 cm³ (class A).

        Burettes measure from the top since they are used to measure liquids dispensed out the bottom. The difference between starting and final volume is the amount dispensed In this test rig, the 3 way locked type burette is employed. It is mainly used for the purpose of measurement of the amount of fuel consumed by the engine during the experiment.

Fig.8 3 Way Burette

The panel board used in the test rig is made up of a ply wood sheet, which is comparatively strong to support the tank fixed above of it. This tank is used to store the fuel, which is diesel here. Manometer and the 3 way burette are fitted on it.

Fig.9 Panel Board

6.    EXPERIMENTAL SET UP

            Our project vision was to construct a test rig for a KAMCO single cylinder diesel engine. This engine was removed from a KAMCO tiller which is commonly used in the paddy and wheat fields. KAMCO tillers are very commonly using tillers all over India in which Kerala government is undertaking this corporation. Thus many subsidies are available for the farmers who are the consumers of this product.

            Any way, we got one piece of such a tiller. Our need was only the engine of that. We have to remove the desired engine from that whole assembly of the tiller which consists of various components. The engine is connected with many accessories in the tiller.

            After the removal of engine from the tiller, it is to be fitted on a concrete basement. We measured the width and length of the engine. Then construction of the concrete basement completed, which has enough space to fix the engine.

Fig.10 C channels bolted on the concrete basement

During the construction of the concrete basement, it was important to leave spaces for placing the foundation bolts. Four foundation bolts are used in this test rig. It is not possible to fix the foundation bolts after concreting. So, space has to be given for that during the concreting

Fixing of the heavy diesel engine in to the concrete basement was a hard task. It was done using ropes which holds the engine by many helpers. After taking the engine to the basement, it was tighten with the C channels by bolting with them. For that, separate holes were already made and it was bolted with the channel by tightening the bolts. An inspection was conducted to make sure that, there is no misalignment in the setup.

Fig.11 taking engine to the concrete basement

 

These foundation bolts were fixed on the concrete basement. After fixing the foundation bolts, next step was to fix the C channels on the basement. Foundation bolts are unavoidable in this step. Four pieces of C channels are supposed to be fitted on the basement with the help of the foundation bolts. Then the C channels were tightly bolted on it. It is very important in the construction of the test rig that, any vibration should not be obtained during the working of engine. So, the C channels where the engine is to be fix should be strong.

Fig.11 Engine fixed on the basement

            This engine is cooled using water cooling system. Although engines have improved a lot, they are still not very efficient at turning chemical energy into mechanical power. Lot of the energy is converted into heat, and it is the job of the cooling system to take care of that heat.

The primary job of the cooling system is to keep the engine from overheating by transferring this heat to the air, but the cooling system also has several other important jobs.

            The cooling system on liquid cooled cars circulates a fluid through pipes and passageways in the engine. As the liquid passes through the hot engine, it absorbs heat and cools the engine. After the fluid leave the engine, it passes through a heat exchanger, or radiator, which transfers the heat from the fluid to the air blowing through the exchanger. Radiator is used to transfer the hot water which is circulating continuously.

            It was really a challenge to replace the cooling system with out radiator. Radiator is the commonly using method used for engine cooling in vehicles. In the case of experimental setup, it is not compulsory and it is not easy place the radiator in it. We have to measure the temperature of the circulating water through the outlet. After the removal of radiator, an external water supply is introduced to the engine.

 

            Outlet   water is collected in a tank, which is made up of sheet metal. It is placed in a four leg stand near the engine. Circulating water after cooling is collected in hot conditions in this tank. It is using to know the level of circulating water. Another thermometer is required to connect in the hot water passage. Temperature reading is very important in this test rig. For making the port for thermometer, a T joint is introduced to the outlet water pipe. This T joint is required to fix the thermometer.

Fig: 11 Thermometer Pocket

 Not only the radiator, but also other accessories such as its head light, etc. has been removed from the whole assembly of tiller. Then the engine is ready for further functions. Its fuel tank was stored separately and it is supposed to be fitted on the panel board. It is later connected to the 3 way burette for measuring the consumption of the fuel at various loads.

  

Another important step was to extend the exhaust pipe from the engine, which can not to be placed inside the laboratory with the engine. If it is placed with the engine, a large amount exhaust gas will be spread in the lab during the working of engine. Exhaust gas is not only the problem, but also loud sound will be making trouble in the laboratory.

To avoid such problems, we were forced to extend the exhaust pipe. Another pipe was used to extend it. It was connected to the exhaust manifold of the engine. The Muffler which is connected at the end of the exhaust pipe was removed. Then the new pipe was introduced, which longs to the outer of the laboratory. For that, hole was created on the wall near to the experimental setup. Muffler is fitted to the pipe at outside of the lab. During this step, a small port was left on the exhaust pipe to place a thermometer for measuring the temperature of exhaust pipe.

This test rig is a typical experimental set up which consists of a number of instruments. They are mainly used for the determination of the efficiency of the given single cylinder diesel engine. The most important part of the test rig is the testing engine. We are using a number of methods in this test rig for determining various parameters of the engine. Important vision of this test rig is to find the performance.

Fig.9 test rig

             Engineering measurements are not as simple as turning on the equipment and reading the numbers. Relevant information can only be extracted from test data obtained from a well-thought-out measurement test plan.

A test plan will draw from the following three steps.

1. Parameter Design Plan: An identification of process variables and parameters and a means for their control.

2. System and Tolerance Design Plan: The selection of a measurement technique, equipment, and test procedure based on the same preconceived tolerance limits for error.

3. Data Reduction Design Plan: A methodology to analyze, present, and use the anticipated data

            Experimental design includes the development of a measurement test plan. Such a plan assists the engineer in achieving an optimization between time, accuracy, and cost expenditure regarding acquiring and analyzing test data versus information obtained.

            In this engine, cooling is done by water. So it will be having an inlet port and exhaust port for the circulation of water through it. Inlet water is taken from the water tank and the exhaust is made to return back to it after its purpose. Thus a cyclic process is taking on. We have attached a thermometer in the passage of the outlet water from the engine to measure the temperature level of the engine. It is fixed permanently on a T joint attached between the outlet ports of the water. Before making it to the outer tank, we made an extra tank to collect the water to know its current level.Important part of this test rig is the section where the brake drum and spring balances are attached.

7.    WORKING PROCEDURE

          The working of this test rig will take place through the following steps given below

1. Fill up the diesel to the fuel tank mounted behind the control panel.
2. Start the engine by rotating the crank, especially at no load only.
3.  Allow the engine to stabilize the speed i.e. 2000 rpm by adjusting the accelerator knob.
4. Apply load by tightening the hand wheels mounted on the loading frame. Then automatically speed will drop, bring back the rated speed by adjusting the hand wheels.
5. Now note down all the required parameters mentioned below:

       a. Speed of the engine.

       b. Load from the spring balance.

       c. Fuel consumption from burette.

       d. Quantity of air flow from manometer.

6. Load the engine step by step.
7. The corresponding parameters have been noticed.
8. Turn off the knob provided on the panel after the test.

Here with the test rig, the loading is done with the help of a mechanical brake drum. Fuel measurement, air intake measurement and temperature measurements are being taken and finally thermal overall volumetric efficiency and brake thermal overall efficiency is being found out.

Finally the performance test is being conducted and the following graphs are been plotted.

a.       Brake power vs. Specific fuel consumption.

b.      Brake power vs. Brake thermal efficiency.

c.       Brake power vs. Volumetric efficiency.

8.    EQUATIONS USED

There are a lot of equations used in this experiment to determine the required parameters.

They are,

1. Brake Power

BP = 2 π N (W – S) (D+ d) / 2) x 9.81   kW

Where,

N         =          rpm of engine

S          =          spring balance reading in kg

W        =          Dead weight in kg  

D         =          dia. of brake drum in m,

d          =          dia. of rope in m,

2. Mass of fuel consumed

                 Mfc = (X × 0.83 x 3600) / (1000 × T) in KG / Hour

                

              Where,

                   

            X        =          burette reading in cc

0.83    =           density of diesel in gram/cc

T        =          time taken in sec

9.      Specific fuel consumption

Sfc       =         (Mfc / BP) kg/ kw hr

Where,

_{Mfc     =          Mass of fuel consumed in Kg}

_{BP       =          Brake Power in KW}

10.  Actual volume of air sucked into the cylinder

Va     =          Cd x A x √2GH x 3600 m³/hr

      

Where,

            H         =          (h/1000) × (density of water / density of air)

........... A         =          Area of orifice = π/4 d²

            D         =          Dia. Of orifice

            H         =          manometer reading in mm

            δw/δa  =         density of water /density of air

            Cd       =          Co-efficient of discharge = 0.62

         

  5. Swept volume

   

           (π/4 d²⁾ × L × N/2 ×60 m³/hr

              Where,

                  

                     ^{d = Diameter of bore in mm}

               ^{L = Stroke Length}

               N = Speed in RPM

           6. Volumetric Efficiency

           η_v    ⁼      _{(Va/ Vs) × 100 %}

              _Where,

                _{Va = actual volume in m3 / hr}

                _{Vs = Swept volume}

          _{7. Brake thermal efficiency}

          

              _{ηbth   = (BP ×3600 ×100) / (Mfc × Cv)}

             _Where,

               _{BP = Brake Power in KW}

               _{Mfc = Mass of fuel consumed in Kg / Hr}

               _{Cv = Calorific value of diesel = 42500}

9.    OBSERVATION AND CALCULATION

                                                                                             

9.1 SAMPLE CALCULATIONS

1.BP = 2 π N (W – S) ((D+d) / 2) x 9.81   kW  

                        =   ( 2 π  Х  (3-1.2) Χ .1125 Х 9.81)/ 60000

                             = 0.4158 kw

2.Mfc = (X × 0.83 x 3600) / (1000 × T)

                 =  ( 5 Х .83 Х 3600 )/ (1000 Х 37)

                      = 0.403 kg/hr

     3.Sfc = (Mfc / BP) kg/kw hr =  0.533/0.808

                                               = 0.659 kg/ kw hr

4. Va = Cd x A x √2GH x 3600 m³/hr

                              where   H =      (h/1000) × (density of water / density of air)

                                               = 28.43

.           Va = 3.14 x10- x0.62  x √(2 x 9.81 x28.43) x 3600

                  =16.55  m³/hr

_{5.      Vs = (π/4 d}²_{) × L × N/2 ×60 m}³_{/hr  =}

                     _{= (π/4 (0.095)}²_{) × 0.105 × (2000/2) × 60}

                     _{= 44.63  m}³_/hr

_{6.      ηv =   (Va/ Vs)  ×  100}

                  _{= 37 %}

_{7.     ηbth   = (BP ×3600 ×100) / (Mfc × Cv)}

         _{= (0.416 × 3600 × 100) / (0.452 × 42500)}

                  = 7.745

Sl No	Brake Power kw	Mass of fuel consumed kg/hr	Specific fuel consumption kg/kwhr	Actual volume of air sucked into the cylinder m/hr	Swept volume m/hr	Volumetric efficiency ηv %	Overall efficiency ηall %
1 2 3 4 5 6 7 8	0 0.416 0.808 1.409 2.125 2.772 3.465 4.504	0.403 0.452 0.533 0.598 0.711 0.747 0.934 1.149	- 1.08 0.659 0.424 0.334 0.269 0.269 0.255	16.55 16.38 16.35 16.35 16.35 16.22 16.12 16.12	44.63 44.63 44.63 44.63 44.63 44.63 44.63 44.63	37.2 36.7 36.6 36.6 36.6 36.3 36.1 36.1	0 7.795 12.84 12.95 25.32 31.43 31.42 33.20

10 .CONCLUSION

Through this test rig, we will be able to conduct the performance test of the KAMCO engine and finally the required graphs are being plotted. The overall efficiency is being calculated and the corresponding graphs has been plotted.