Design And Operation Of Engine Testing Facilty Engineering Essay
ABSTRACT
The report covers design and development of an engine testing facility for the operation of diesel and gasoline engines. It consists of two sub-cells for each engine type. It is designed by keeping Euro 5 emission standard in mind.
A study was made to find the power output of the diesel engines of 1.3 lit. Turbo to 6.0 lit. Tdi and gasoline engine of 1.6 lit. With variable vane turbo charger and variable geometry valve timing. The Heat balance sheet for both the engine and the test cell was made on the basis of power output. afterwards, the mass flow rate of the fuel, air, cooling water and oil were calculated to design the test cell. The dynamometer and other equipments were selected based on their types and operation requirements. At the end the bill of material of all the parts purchased was prepared to illustrate that the designed testing facility meets the funds of the project.
TABLE OF CONTENTS
ABSTRACT
Introduction 5
Test Cell Facilities
Typical Test Cell Layout
Thermodynamics of the test cell and flow measurement 7
Energy Balance
2.2.1Diesel Engine Energy Balance
2.2.2 Diesel Cell Energy Balance
2.3.1 Gasoline Engine Energy Balance
2.3.2 Gasoline Cell Energy Balance
Test Cell Design
Individual Test Cell Size
Test Cell Design
Cell Services
Diesel Test Cell Layout
Dynamometers
Dynamometer mechanism
Dynamometer Types
Selection Of Dynamometer
Instrument Selection
5.1Engine Speed
5.2 Temperature Measurement
5.3 Flow Rates Measurement
5.4 Pressure Transducers
5.5 Emission Equipment
5.6 Smoke Measurement
5.7 Prices of the Instruments
Conclusion
Reference
CHAPTER 1
INTRODUCTION
In the present scenario, internal combustion engines have become the most widespread form of energy conversion from chemical to mechanical form. A lot more is going on these days to improve the design of the engine using better materials and techniques in order to achieve more power and fuel economy. Considering the amount of effort that is being put to design an engine from scratch, the art of testing an engine is becoming much harder to master. The work of designing a test cell which should test engines with varied range of power output and size requires not only the skill and technical knowledge of the subject; it also requires the exposure to the new and developing experimental techniques to observe even the minute aspect of the project in order to design the best possible layout. The testing of an engine requires correctly measuring the parameters such as temperatures, air flow, fuel flow, air velocity and several meter readings in the first attempt itself as it’s an expensive exercise to conduct an engine test. [2]
1.1 TEST CELL AND FACILITIES
To build a test cell requires a detailed study of the energy input and output with respect to the engine, size of the engine etc. So the proper plan has to be carried out. The test facility should be well equipped with the modern test equipments and instruments like gas analyser, transducers etc. Following topics discussed the facilities.
1.2 A Typical Test Cell Layout
The following fig. shows a typical cell layout showing the different systems like ventilation for air, conditioning systems, data acquisition, cooling and air conditioning system etc..
Fig. 1.1 A typical Test cell layout
CHAPTER 2
ENERGY BALANCE AND MEASUREMENT
2.1 ENERGY BALANCE
With reference to the table and the figure, an energy balance of the 1.3 litres turbo engine (manufactured by FIAT), which produces a power of 95bhp @4000 rpm (equivalent to 70 KW) is carried out. The same procedure can be later followed to calculate the energy flows for the 6.0 litre Tdi V12 Volkswagen engine producing a power of 331 KW @6050 rpm & 560 Nm of torque at 2750 rpm.
2.2.1 DIESEL ENGINE ENERGY BALANCE
Engine: 1.3 litre turbocharged diesel engine, power output: 95 bhp(70.87 KW)
Assuming thermal efficiency of the engine = 0.42,
calorific value of diesel = 44.8 MJ/kg
So, fuel input power = 70.87/0.42 = 168.73 KW
Specific fuel consumption =
Table 2.2 Energy Balance for the fiat 500 1.3 litre turbocharged 70.87 KW diesel engine
Item
Energy In
Item
Energy Out
Fuel
168.73KW
Power
70.87KW (42%)
Heat to cooling water
33.746KW(20%)
Heat to oil cooler
5.0619 KW (3%)
Heat to exhaust
42.1825KW(25%)
Conv. and Radiation
16.873KW(10%)
Total
168.73 KW
168.73 KW
Flow Rate Calculations:
Mass flow rate of the fuel: =
The density of diesel fuel is ÃÂ = 0.832 Kg / lt
So, the fuel flow rate is: = 16.0096 litres / hr.
Air flow: : Assuming that the air-fuel ratio at full load is 25:1 and
air density is 1.2 Kg /,
= 333 Kg / hr. = 333.5/1.2 = 277.5 m3/hr.
Cooling water flow : : Heat loss to the cooling water is assumed to be 20%
Therefore, Heat loss =
Assuming 10 degrees rise in the water temperature
= 48.4392 kg/min
Exhaust flow : = 346.32 Kg/hr
Engine: Volkswagen 331 KW, 450 BHP engine
The energy balance and mass flow rates for this engine was calculated by similar fashion as shown in the above case.
Table 2.3 Energy Balance for the Volkswagen 331 KW,450 bhp engine:
Item
Energy In
Item
Energy Out
Fuel
788.09KW
Power
331 KW (42%)
Heat to cooling water
157.6KW(20%)
Heat to oil cooler
23.64 KW (3%)
Heat to exhaust
197.02 KW (25%)
Conv. and Radiation
78.809KW(10%)
Total
788.09 KW
788.09 KW
Table 2.4 Flow rates for the Volkswagen 331 KW engine:
Particulars
Mass flow rate
Fuel
63.3286 kg/hr
Air
1583.21 /hr
Cooling Water
226.22 kg/min or lts/min
Exhaust
1583 kg/hr
2.2.2 DIESEL CELL ENERGY BALANCE
The energy balance for the diesel cell has been shown the table 2.5. Some of these calculations are being done in the ventilation system section.
Table 2.5 Energy balance for the diesel test cell for 450 BHP diesel engine
Item
Energy In
Item
Energy Out
Fuel 788.09 KW
Exhaust Gas 150 KW
Ventilation Fan Power 10 KW
Dynamometer Power 373 KW
Electrical Cell Services 25 KW
Engine Cooling Water 157.6 KW
Ventilation Air 150.868 KW
Cell Wall Losses 5 KW
Total 823.09 KW
Total 823.09 KW
2.3.1 GASOLINE ENGINE ENERGY BALANCE
This cell is required to test the engines from 1.6 litre variable vane turbocharger with variable valve timing to 3 litres 400 BHP engine.
Engine: Toyota corolla 1.6 litre VVT, 110 rpm, 150 rpm
The energy balance and flow rate calculations are same as that of the previous. Assuming 30 30-30-10 thumb rule. The calorific value of petrol is = 48000 KJ/kg.
Table 2.6 Energy Balance for the Toyota corolla1.6 litre 80 KW petrol engine
Item
Energy In
Item
Energy Out
Fuel
267KW
Power
80 KW (30%)
Heat to cooling water
80 KW (30%)
Heat to exhaust
80 KW (30%)
Conv. and Radiation
27 KW (10%)
Total
267 KW
267 KW
The 30-30-30-10 rule is used for the assumption that means assuming 30% thermal efficiency of the engine and the fuel power input has been calculated on this basis. Later, 30% heat loss is carried away by the engine cooling water and the exhaust of the engine. The 10% heat is lost to the surrounding air by convection and radiation.
Following table represents the various flow rates for the engine assuming the air – fuel ratio at full load to be 15:1 for the gasoline engines.
Table 2.7 Flow rates for the Renault 1.6 litres VVT 80 KW engine
Particulars
Mass flow rate
Fuel
20 kg/hr
Air (A:F = 15:1)
250 /hr
Cooling Water
115 kg/min or lts/min
Exhaust
320 kg/hr
Engine: A 3.0 litre 400 BHP (294 KW) gasoline engine
Energy balance and flow rates have been calculated similarly as previous cases.
Table 2.8 Energy Balance for the 3.0 litre 400 BHP petrol engine
Item
Energy In
Item
Energy Out
Fuel
980KW
Power
294 KW (30%)
Heat to cooling water
294 KW (30%)
Heat to exhaust
294 KW (30%)
Conv. and Radiation
98 KW (10%)
Total
980 KW
980 KW
The values shown in the above table have been calculated assuming the 30-30-30-10 rule as discussed in the previous section and the table below shows the various flow rates for the gasoline engine.
Table 2.9 Flow rates for the Renault 1.6 litres VVT 80 KW engine
Particulars
Mass flow rate
Fuel
73.5 kg/hr
Air (A:F = 15:1)
920 /hr
Cooling Water
422 kg/min or lts/min
Exhaust
1178 kg/hr
2.3.2 GASOLINE CELL ENERGY BALANCE:
The table below represents the energy flows in and out of the cell when operating on full capacity of 400 BHP gasoline engine
Table 2.10 Energy balance for the gasoline test cell for 400 BHP engine
Item
Energy In
Item
Energy Out
Fuel 980 KW
Exhaust Gas 274 KW
Ventilation Fan Power 5 KW
Dynamometer Power 250 KW
Electrical Cell Services 25 KW
Engine Cooling Water 294 KW
Ventilation Air 187 KW
Cell Wall Losses 5 KW
Total 1010 KW
Total 1010 KW
The energy balance sheets for the diesel and gasoline engines lay a firm foundation for the design of the in-cell services and selection of the equipments that have been carried out in the later chapters.
CHAPTER 3
3.2 TEST CELL DESIGN
The test cells must be provided with the following services:
Water supply and drainage system
Fuel supply system
Ventilation system
Taking engine exhaust to exterior
Fire and safety regulations
Portable test stand for the engine and dynamometer
Control room or console etc…
We have to keep the temperature maintained at the ambient, so we have to give importance to ventilation system also.
General purpose engine test cell has been shown in fig. 3.1. A typical test cell layout that has been used for these types of engines has also been shown in the fig. 3.2. Such type of cells is usually built side – by – side with common control room. The engines are imported in the cell from the rear – door whereas the operator could enter from the front door. A thick glass is mounted between the control room and the engine cells so the operator could have a look at the cells while sitting inside the control room. [1]
Fig. 3.1 General arrangement inside an engine cell aligned against a wall and the control room on the other side of the engine.
Fig. 3.2 A layout of the test facility with two cells having a common control room ..
Fig. 3.1 and 3.2 shows the typical layout of a facility incorporated with two separate cells and a common control room with a thick glass window separating the cell and the control room. The cells are aligned with a wall which leads the exhaust outlet to the atmosphere.
3.3 CELL SERVICES
3.3.1 VENTILATION SYSTEM
Ventilation system plays a very important role in any engine testing laboratory or testing cell. inside the cell due to running of heavy engine a high temperature is developed also at the surface of the engine . so it is necessary to carry away this heat ventilation system should be strong enough , also it is necessary to keep the surrounding temperature at ambient conditions.
The convection and radiation losses are assumed as below (based on diesel engine):
Engine
78.809 KW (10% as mentioned in heat balance)
Exhaust Manifold
10 KW
Exhaust tailpipe and silencer
10 KW
Dynamometer
40 KW
Electrical equipments
15 KW
Forced draught fan
5 KW
Subtotal
158.809 KW
Total (assuming 95% efficiency of the ventilation system)
150.868KW
Table 3.2 Heat losses to be considered for the ventilation system design
For the total heat loss from engine by convection and radiation H = 150.868 KW, the volume flow rate of air can be calculated as:
Taking H = 150.868 KW, C = 1.01 KJ/Kg-K, ÃÂ = 1.2 kg/m3, and temp rise of 10, the mass flow rate is: 12.447 m3/sec. or 746.87 m3/min.
the air flow velocity in the duct could be taken in between 15-20 m/sec. For this value, the cross-sectional area could be 0.37-0.49 m2. So, from a range of standard duct area, it could be taken as 600mm X 600mm ( square duct) as it results into the air flow velocity of 19.5m/sec (satisfies the range of 15-20 m/sec) and velocity pressure or dynamic pressure of 228 Pa. [3] from the above data centrifugal and axial fans were selected for the inlet and outlet respectively . typical ventilation system is as shown in the fig.
Specification of the fan used in the ventilation system is as follows:
Fan
Air vol. (m3/hr)
Speed (rpm)
Power (KW)
Centrifugal
920
2250
0.29
Axial
958
1680
0.21
Table 3.4 represents the specification of fans selected for ventilation
3.3.3 COOLING WATER SYSTEM
Water is an almost ideal cooling fluid as it has a high specific heat value, low viscosity, relatively low corrosivity and is freely available (Martyr and Plint, 2007). The required flow rates can be calculated similarly to that of air if the heat to be transferred and the change in temperature is known. Additives such as ethylene glycol (antifreeze) can be added to the water to improve the operating temperature range of the cooling system and inhibit corrosion, although the specific heat value will be reduced.
There are various types of cooling water circuits that can be considered like:
Open water circuit, where the water is supplied directly from the mains and is therefore not circulated back.
Closed water cooling circuits, where the water is supplied from a sump or tank and can be circulated back. This has an advantage that the coolant could me mixed in water sump to improve the cooling effect.
Closed pump circuit
3.4 DIESEL TEST CELL LAYOUT
C:UsersrohitDesktopdiesel cell layout.png
Fig. 3.4 The diesel cell layout base on all the calculation done
CHAPTER 4
DYNAMOMETERS
Dynamometers are used inside the test cell to measure the torque which developed on the engine output shaft. It also measures the power output of the engine.
4.1 WORKING OF DYNAMOMETER
Fig. 4.1 typical setup of dynamometer
The dynamometer resists the rotation of the engine shaft to measure its torque. The rotor rotates inside the stator which as the name indicates is stationary. The rotor exerts torque on the stator and this balanced by the load cell. The toque is given by:
T = F X B
And so the power developed by the engine could be known as:
P = 2ÀNT KW
If the engine speed (in rpm) is measured using tachometer, the power could be easily calculated using the above equation.
4.2 TYPES OF DYNAMOMETER :
The dynamometer types which are in practice include:
Hydraulic Dynamometer
DC Dynamometer
AC Dynamometer
Eddy current Dynamometer
Each one of the above mentioned dynamometers has different set of working principle. There are four quadrants in which a dynamometer can operate: rotating clockwise producing or absorbing torque and rotating counter clockwise producing or absorbing torque. Figure gives a diagrammatical layout of these four quadrants. Most water brakes can only operate in the first quadrant. Eddy current dynamometers can operate in the first two quadrants, while AC/DC dynamometers can be used in all four quadrants.
Figure 3-13: Dynamometer operating quadrants (Martyr and Plint, 2007)
4.3 DYNAMOMETER SELECTION:
Different types of dynamometer has been studied by considering the advantage and disadvantage of each type of dynamometer the AC dynamometer has been chosen as it can perform in all the four quadrants and has lower inertia than the DC dynamometers, which makes it less vulnerable to vibrations due to rotation of the shaft.
Diesel Cell:
As the cell has been designed to fit in the engine ranging from 75-500 BHP. The dynamometer selected for this cell is AC – 500 – 1811. 373 kw manufactured by Mustang dynamometer . The specifications are listed in table 4.2:
Horsepower
Cooling Type
Constant torque range(ft-lb)
Max Torque (ft-lb)
500
Blower
2455
2455
Table 4.2 AC dynamometer selected for diesel cell
Gasoline Cell:
The gasoline cell has been designed in such a way that it will test the engine with a maximum of 400 BHP.
The selected dynamometer was AC – 400 HP dynamometer manufacture by Dyne systems and its specifications are listed in the table 4.3
Horsepower
Constant Torque range (ft-lb)
Constant HP range
Max Torque (ft-lb)
400
1175
3525
1787.91
Table 4.3 AC dynamometer selected for the gasoline cell
CHAPTER 5
SELECTION OF INSTRUMENTS
5.1 SHAFT SPEED MEASUREMENT
Tachometer is used for the engine speed measurement the non contacting digital tachometer is used so that it will not affect on the speed of the shaft . following tachometer is selected
Make: Check-line ltd, Model: ctd-1000hd, Non-contact type, Measuring rang : 1.00-99999 Rpm, Prize:
5.2 TEMPERATURE MEASUREMENT
The inlet air, coolant inlet and outlet, exhaust and oil temperatures can be measured with thermocouples. Depending on the temperature to be measured, K and J type Thermocouples are the most common thermocouples available. J types operate in a smaller range, approximately to 150°C while K types operate up to 1500°C
5.3 FLOW RATE MEASUREMENTS
a) Turbine-flow meter: Omega, model: FTB790 Series. It has an output range of 0-5V DC
b) Fuel-flow meter: Fischer-Porter Digital fuel flow meter is selected
c) Air-flow meter: Mass-air flow meter manufactured by Shijiazhuang Fortune Industrial & Trading Co., Ltd. and FHC Ind, model: FHC-CMF I-DNXX Limited has been selected. temp range of -40 to 200.
5.4 PRESSURE TRANSDUCERS
Omega high accuracy pressure transducer has been selected Model: PX01C1 -100G5T 5. Range: 0-400 bar, with 0 to 5 Vdc Output accuracy .
5 EMISSION EQUIPMENT
The equipments used should be of euro 5 standards following chart shows the emission norms for euro 5 and euro 6 standards:
EURO 5
EURO 6
PERTOL
DIESEL
PETROL
DIESEL
CO
1
0.5
1
0.5
THC
0.1
–
0.1
–
NMHC
0.068
–
0.068
–
NOX
0.06
0.18
0.06
0.08
HC+NOX
–
0.23
–
0.17
PM
0.005
0.005
0.005
0.005
Fig. 5.2 EURO 5 and EURO 6 emission standards
Exhaust gas analyser:
XM2000 5 -gas analyser Exhaust Measurement System provides a portable, low cost tool for continuous analysis of engine exhaust gas components (HC, CO, CO2, NO, O2) system. XM2000 -gas analyser manufactured by Dyne Systems Inc.
5.6 PRICE-LIST
Items
Price (
Reason for purchase
Dynamometers
1,20,000
Power and Torque measurement
Centrifugal Fans
500
Forced Draught
Axial Fans
1800
Ventilation Exit
Feet levelling for beds
700
Absorb vibrations
6 thermocouples
100
Temp. measurement
2 Infrared thermometers
280
Non-invasive temp.
2 Digital Tachometers
125
Engine Speed measurement
2 Data-Acquisition System
1,10,000
Record and transfer data to control room
2 Pressure Transducers
700
Cylinder Pressures
All types of flow meters
10,000
Measure mass flow rates
Gas Leak Detectors
400
To detect leaks
Smoke Detectors
50
To detect fire
5-Gas Analyzers (2nos)
4,50,000
To check emission
TOTAL COST