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5/18/2018 ExperimentNo.52-slidepdf.com http://slidepdf.com/reader/full/experiment-no-5-2 1/20 Experiment No. 5 TEST OF OXYGEN BOMB CALORIMETER: OBTAINING THE CALORIFIC VALE OF FEL Co!r"e Co#e: MEF$%&L% 'ro(r)m: BSME Co!r"e Tit*e: ME L)+or)tor, % -)te 'erorme#: Fe+r!)r, //0 %&/5 Se1tion: ME$%FA/ -)te S!+mitte#: M)r12 /0 %&/5 Mem+er": /. 3)r)0 C2)r*e" 4o!r#)n M. Le)#er6 In"tr!1tor: En(r. Ne*"on -e*)'e7) 4r.  %. Ar1),0 An#re8  9. C)rin()*0 4o2n M)rtin . S)et, Oi1er6  $. -e*) 1r!0 4o2n ;e*<in B.  5. G)e*)0 V)n=o12ri"  >. M)1)p)()*0Roe* . ?!)*it, Contro*6 /. O+=e1ti<e"6: The activity aims to demonstrate how to determine the calorific value of different types of fuel. %. Inten#e# Le)rnin( O!t1ome" ILO"6: The students shall be able to: 2.1 Perform the procedure of operating an oxygen bomb calorimeter. 2.2 Determine the calorific value of different types of fuel. 2.3 Develop professional wor ethics! including precision! neatness! safety and ability to follow instruction. 9. -i"1!""ion: "alorimetry is a fundamental test of great significance to anyone concerned with the production or utili#ation of solid or li$uid fuels. %ne of the most important tests in the evaluation of materials! which are burned! as fuels! is the determination of the heat of combustion! or calorific value. These measurements can be made in the &omb "alorimeter 'et for Testing "alorific (alue of )uels! T&"). The &omb "alorimeter is a classic device used to determine the heating or calorific value of solid and li$uid fuel samples at constant volume. &asically! this device burns a fuel sample and transfers the heat into a nown mass of water. )rom the weight of the fuel sample and temperature rise of the water! the calorific value can be calculated. The calorific value obtained in a bomb calorimeter test represents the gross heat of combustion per unit mass of fuel sample. This is the heat produced when the sample burns! plus the heat given up when the newly formed water vapor condenses and cools to the temperature of the bomb. Determining calorific values is profoundly important* fuels are one of the biggest commodities in the world! and their calorific value. The &omb "alorimeter study is carried out to gain a better understanding of the woring principles behind the bomb calorimeter and also to find out the gross calorific values of different types of li$uid fuel.

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lab 2

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Experiment No. 5

TEST OF OXYGEN BOMB CALORIMETER: OBTAINING THE CALORIFIC VALUE OF FUEL

Course Code: MEF420L2Program: BSME

Course Title: ME Laboratory 2Date Performed: February 11, 2015

Section: ME42FA1Date Submitted: March 1, 2015

Members: 1. Zafra, Charles Jourdan M. (Leader)Instructor: Engr. Nelson DelaPea Jr.

2. Arcay, Andrew

3. Caringal, John Martin U. (Safety Officer)

4. Dela cruz, John Kelvin B.

5. Gaela, Vanjochris

6. Macapagal,Roel U. (Quality Control)

1. Objective(s):

The activity aims to demonstrate how to determine the calorific value of different types of fuel.

2. Intended Learning Outcomes (ILOs):

The students shall be able to:2.1 Perform the procedure of operating an oxygen bomb calorimeter.2.2 Determine the calorific value of different types of fuel.2.3 Develop professional work ethics, including precision, neatness, safety and ability to follow instruction.

3. Discussion:

Calorimetry is a fundamental test of great significance to anyone concerned with the production or utilization of solid or liquid fuels.

One of the most important tests in the evaluation of materials, which are burned, as fuels, is the determination of the heat of combustion, or calorific value. These measurements can be made in the Bomb Calorimeter Set for Testing Calorific Value of Fuels, TBCF.

The Bomb Calorimeter is a classic device used to determine the heating or calorific value of solid and liquid fuel samples at constant volume. Basically, this device burns a fuel sample and transfers the heat into a known mass of water. From the weight of the fuel sample and temperature rise of the water, the calorific value can be calculated. The calorific value obtained in a bomb calorimeter test represents the gross heat of combustion per unit mass of fuel sample. This is the heat produced when the sample burns, plus the heat given up when the newly formed water vapor condenses and cools to the temperature of the bomb. Determining calorific values is profoundly important; fuels are one of the biggest commodities in the world, and their calorific value.

The Bomb Calorimeter study is carried out to gain a better understanding of the working principles behind the bomb calorimeter and also to find out the gross calorific values of different types of liquid fuel.

Description:The unit comprises the calorimeter, a calorimeter vessel, an outer double walled water jacket, control unit to switch on/off the stirrer and the ignition device, a Beckman type thermometer, and charging unit with pressure gauges to facilitate the charging of the calorimeter with oxygen. The particular features of the calorimeter bomb are the method of sealing and the method of ensuring ignition. The calorimeter vessel and outer jacket wall are manufactured in stainless steel. The calorimeter bomb is a container made of stainless steel that can support high pressures. It is sealed by a screw top. The bomb is charged with gas (oxygen) through the filling valve. This bomb is introduced inside a calorimeter vessel made of stainless steel that is filled with water, and at the same time it is introduced inside a double walled water jacket.

The rod of the calorimeter supports a metallic crucible. The calorimeter bomb, which contains the fuel sample to be burned, is hermetic to the gas by closing the filling valve and its cover. Combustion is started through a thin wire that is red hot-heated up momentarily due to the passing of an electrical current that flows through an isolated terminal and the rod, which is electrically connected to the cover.

The water in the calorimeter vessel is agitated automatically with a stirrer driven by a small motor. The top of the double walled jacket is closed with a cover that has some orifices. A Beckman thermometer to measure the temperature of the calorimeter vessel passes through one of these orifices. Other orifices are used to fasten the jacket to the cover. Also, one of these holes is used to insert the wire that supplies the electric current to the rod. The unit includes a control unit that switches on/off the stirrer and the ignition device through the heating up of the thin wire, and a load unit with pressure gauges to make the filling with oxygen of the calorimeter easier.

Specifications:

Calorimeter for testing calorific value of fuels, including: 1. Main metallic elements in stainless steel. 2. Diagram with a distribution of the elements similar than the one in the real unit. 3. Calorimeter bomb. 4. Calorimeter vessel. Characteristics: o Stainless steelMaximum volume: 4 litters. 5. Double walled outer jacket in stainless steel, with water inlet and outlet. 6. Electric stirrer with one rod and two blades. Characteristics: 330rpm. 7. Control unit to switch on/off the stirrer and the ignition device 8. Beckman thermometer. Range: 6C. 9. Charging unit with pressure gauges. 10. One nickel crucible. 11. Reel of Nickel-Chrome wire.

Dimensions: 500 mm x 400 mm x 1000 mmVolume: 0.2 m3 Weight: 40 kgElectrical Supply: single-220V/50Hz or 110V/60HzWater: 7.7 LiterOxygen CylinderSeveral Types of Fuel: Benzoic Acid (C7H6O2)

Theoretical Consideration:Almost all chemical reactions adsorb or release energy, generally as heat. Heat is the thermal energy transfer between two bodies whose temperatures are different. Heat flow from a hot body to a cold one is frequently mentioned. Generally, absorbed heat or released heat is used to describe the energy changes that take place during a process.

Reactions that take place during a process can be endothermic, if they absorb heat, or exothermic, if they release heat. Endothermic changes are expressed with a positive sign, and exothermic changes with a negative sign, according to the first law of thermodynamics. The enthalpy change occurred in the direct reaction is exactly opposed in the inverse reaction. This thermal effect is the same regardless whether the reaction takes place in one or several stages. The magnitude of the change depends on the composition, the physical state of the reagents and products and the stoichiometric expression.

Thermal changes can happen at constant pressure or at constant volume and are expressed with the following equations:

H = qp = 0

E = qv = 0

Where: H represents the enthalpy change and E represents the energy change. The H can be experimentally determined by measuring the heat flow that accompanies a constant pressure reaction, and the E a constant volume.

Heat changes of physical or chemical processes are measured with a calorimeter, which is a closed vessel specifically designed for that purpose. The calorimetry study, that is to say, the measurement of heat changes, depends on the understanding of specific heat and heat capacity. The specific heat (cp) of a substance is the amount of heat required to increase one Celsius degree the temperature of one gram of the substance. The heat capacity (Q) of a substance is the amount of heat required to increase one CelsiusDegree the temperature of a certain amount of substance. The relationship between the heat capacity and the specific heat of a substance is:

Q = mcpWhere m is the mass of the substance in grams and cp is the specific heat of a substance

The Heat of Combustion and Its Determination:Fuels are those substances predominantly containing carbon, or carbon and hydrogen, or carbon, hydrogen and oxygen, which are utilized for the energy they produce upon union with oxygen. The products of combustion are carbon dioxide, water and other oxides. The amount of heat given out in a chemical reaction depends on the conditions under which the reaction is carried out. The standard heat of reaction isthe heat released when the reaction is carried out under standard conditions: pure components, pressure (1 atm.) and temperature, usually but not necessarily, at 25C.

The Heat of Combustion (Calorific Value or Heat Value) of a compound is the standard heat of reaction for complete combustion of the compound with oxygen. The terms higher calorific value (HCV) and lower calorific value (LCV) are used, respectively, to distinguish the cases in which any water formed is in the liquid or gaseous phase. The two calorific values are related as follows:

HCV = LCV + (mw x LH)

Where mw is the mass of water produced per unit mass of fuel and LH is the latent heat of evaporation of water.

The Bomb Calorimeter:The heat of combustion is a required value in the design of any type of combustion system. There are two methods for its determination one by calculation based on the chemical composition and other by actual combustion in a bomb calorimeter. For fuels with complex chemical formulae, it is more reliable and simpler to evaluate the heat of combustion by doing a bomb calorimeter test. Further, if there is any doubt in the composition and structure of a fuel or the formula for calculating the heat of combustion, it may prove more reliable to perform the bomb calorimeter test, as it is a direct measure of the heat of combustion.

Bomb calorimeters for rapid combustion are composed of a combustion chamber (bomb) and a calorimeter vessel, usually a cylinder surrounding the bomb and containing a known quantity of water. The elevation in temperature of that water will be measured. The combustion is made in oxygen, pure or diluted. Combustion chambers are either under a constant pressure or with a constant volume. The results obtained with a calorimeter of constant volume are not exactly the same as those obtained with constant pressure, but for solid or liquid substances the difference is too small to consider.

Set of Bomb CalorimeterThe instrument consists of (1) the bomb; (2) the water container where the bomb is placed and (3) a surrounding compartment of temperature controlled water. The bomb is a small cylindrical pressure vessel with a tight fitting head clamped on the external face of the bomb by a screw cap, a port for a pressure relief valve and two ports for the two electrodes. The material to be combusted is placed in a metal cup that is suspended in the bomb by two supports that also are part of the electrical circuit containing the fuse wire. The fuse wire spans across the top of the metal cup. When current is passed through the fuse wire, it heats up rapidly and ignites the fuel.The bomb is placed in a container with a known amount of water, together with an agitator and a thermometer. The agitator is used to maintain a uniform temperature in the water and aids the heat transfer

from the bomb. The thermometer measures the water temperature (its range is from 24C to 30C with 0.01C accuracy). There is an air gap between the water vessel and the water jacket, which is an excellent heat insulator. When the calorimeter is running, the temperature of the calorimeter body is automatically maintained at the same temperature than that of the water container that holds the bomb. This provides an adiabatic condition and, thus, no heat is transferred to or from the container of water, except from the heat released in the bomb.

4. Materials and Equipment:

Bomb Calorimeter Set for Testing Calorific Value of Fuels, TBCF Different kinds of fuels

5. Procedure:

1. Prepare the fuel sample by placing it in a crucible and weighing it on a balance. Ensure that the weight of the fuel does not exceed 1.1 g. Note down the weight of the fuel sample (mf) and place the crucible containing the fuel gently in the loop holder. When starting tests with new or unfamiliar materials, it is always best to use samples of less than 0.7 of a gram, with the possibility of increasing the amount if a preliminary test indicates no abnormal behavior.

2. The bomb head has been pre-attached with a 10 cm long fuse wire between the two electrodes. Bend the fuse wire down just above the liquid fuel sample. The wire must not make contact with the fuel crucible. To attach the fuse to quick-grip electrodes, insert the ends of the wire into the eyelet at the end of each stem and push the cap downward to pinch the wire into place. No further threading or twisting is required.

3. It is not necessary to submerge the wire in a powdered sample. In fact, better combustions will usually be obtained if the loop of the fuse is set slightly above the surface. When using pelleted samples, bend the wire so that the loop bears against the top of the pellet firmly enough to keepit from sliding against the side of the capsule.

4. Care must be taken no to disturb the sample when moving the bomb head from to the calorimeter bomb. Check the sealing ring to be sure that it is in good condition and moisten it with a bit of water so that it will slide freely into the body of the calorimeter bomb, then slide the head into the bomb and push it down as far as it will go. Set the screw cap on the bomb and turn it down firmly by hand to a solid stop. When properly closed, no threads on the bomb should be exposed.

5. Oxygen for the bomb can be drawn from a standard commercial oxygen cylinder. Connect the regulator to the cylinder, keeping the 0-55 atm. in an upright position.

6. The pressure connection to the bomb is made with a slip connector on the oxygen hose which slides over the gas inlet fitting on the bomb head. Slide the connector onto the inlet valve body and push it down as far as it will go.

Close the outlet valve on the bomb head; then open or crack the oxygen tank valve not more than one-quarter turn. Open the filling connection control valve slowly and watch the gage as the bomb pressure rises to the desired filling pressure (30 atm.); then close the control valve. The bomb inlet check valve will close automatically when the oxygen supply is shut off, leaving the bomb filled to the highest pressure indicated on the 0 - 55 atm. Release the residual pressure in the filling hose by pushing downward on the lever attached to the relief valve. The gage should now return to zero.

7. Fill the calorimeter vessel by first taring the empty vessel; then add 3700 grams of water. Note the exact mass of the water.

8. Introduce the bomb calorimeter inside the calorimeter vessel. Handle the bomb carefully during this operation so that the sample will not be disturbed.

9. Check the bomb for leaks before firing. If any gas leakage is indicated, no matter how slight, DO NOT FIRE THE BOMB. Instead remove it from the water bath; release the pressure and eliminate the leak before proceeding with combustion test.

10. Fill the jacket with water.

11. Put the cover on the jacket. Turn the stirrer by hand to be sure that it runs freely and start the motor. Install the Beckman thermometer; this thermometer should be immersed in water and not close to the bomb.

12. Let the stirrer run for at least 5 minutes to reach equilibrium before starting a measured run.

13. The scanning of the temperature data is pre-set to be done once a minute. At the start of the 5th minute, fire the charge by pressing the firing button on the control unit, keeping the circuit closed for about 5 seconds.

14. The vessel temperature will start to rise within 20-30 seconds after firing. This rise will be rapid during the first few minutes; then it will become slower as the temperature approaches a stable maximum as shown by the typical rise curve shown in Figure. Accurate time and temperature observations must be recorded to identify certain points needed to calculate the calorific value of the sample.

15. Usually the temperature will reach a maximum; then it will drop very slowly. But this is not always true since a low starting temperature may result in a slow continuous rise without reaching a maximum. As stated above, the difference between successive readings must be noted and the readings continued until the rate of the temperature change becomes constant over a period of 5 minutes.

16. After the last temperature reading, stop the stirrer. Let the bomb stand in the calorimeter vessel for at least 3 minutes. Then, remove the jacket cover and extract the bomb calorimeter. Wipe the bomb with a clean towel.

17. Open the valve knob on the bomb head slightly to release all residual gas pressure before attempting to remove the screw cap. This release should proceed slowly over a period of not less than one minute to avoid entrainment losses. After all pressure has been released, unscrew the cap; lift the head out of the cylinder. Do not twist the head during removal. Pull it straight out to avoid sticking. Examine the interior of the bomb for soot or other evidence of incomplete combustion. If such evidence is found, the test will have to be discarded.

18. Remove all unburned pieces of fuse wire from the bomb electrodes.

19. On completion of experiment, wash all inner surfaces of the bomb and the combustion crucible with a jet of distilled water and collect the washings. Keep the bomb set dry and clean with some wiping tissue.

6. Data and Results:

Method of Obtaining the Calorific Value from the Obtained Data:

To illustrate the method of working out the calorific value, the following example of a test is given:

Weight of fuel oil = Weight of crucible and fuel sample - Weight of crucible

Total equivalent weight of water = Weight of water in calorimeter + Water value of unit

Time and Temperature Readings:

Preperiod:

Time (minutes)Thermometer Readings (C)

0

25.3

1

25.3

2

25.4

3

25.5

4

25.6

5

25.6

Rise Period:Time (minutes)Thermometer Readings (C)

5.3025.9

626

726.1

826.2

926.3

1026.4

1126.5

1226.6

1326.6

1426.6

1526.6

1626.6

1726.6

1826.6

1926.6

2026.6

2126.6

2226.6

2326.6

2426.6

2526.6

2626.6

2726.6

2826.6

2926.6

3026.6

3126.7

3226.7

3326.7

3426.7

3526.6

Radiation Correction:The radiation correction is calculated from the knowledge of the rates of change of temperature of the water before igniting the fuel sample and after the attainment of the maximum temperature. Let: n= number of minutes between the ignition and the attainment of the maximum temperaturetf= rate of temperature fall in degrees per minute at the end of the exercisetr= rate of temperature rise in degrees per minute at the beginning of the exercise.

Then the radiation correction is:

Radiation Correction = n x tf+ (tf - tr)/2

This is an approximation to the Renault-Stohman-Pfaundler formula, and is sufficiently accurate for all purposes other than research.

7. Computation, Analysis and Interpretation of Data:

Reactant Product

C7H6O2 + xO2= yCO2 + zH2O

Balancing:

C7H6O2 + 7.5O2=7CO2 + 3H2O

C = 7, H = 6, O = 17

Lower Heating Value:

H2O(L) H2O(g) = 44.0 KJ

3H2O(L) 3H2O(g) = (3 x 44.0 KJ) = 132.0 KJ

LHV = 132.0 KJ

Mass of Water:

Q = mw Cpw (T2 T1)

HVacidmacid = mw Cpw (T2 T1)

mw =

mw =

mw = 4 418.677 g or 4.4187 kg

Higher Heating Value:

HHV = LHV + LH mw

HHV = 132.0 KJ + (2257 )(4.4187 kg)

HHV = 10 104.95 KJ

Molecular Formula (Benzoic Acid)

C7H6O2

Mass of Acid

0.7 gram

Heating Value of Acid26 430

Mass of Water

4.4187 kg

Specific Heat of Water 4.186

Temperature Change

1

LHV

132.0 KJ

HHV

10 104.95 KJ

In this given graph, the result successfully show that the fuel (Benzoic Acid) was burned correctly. Though it only rises 1 due to the mass of the fuel because the fuel contain in the crucible was less than one gram. The graph of the fuel presents the before and after burning the fuel. The first five minutes shows the graph of the initial temperature of the water. The next minutes show the rising temperature of the water; this is the time when the fuel is burning. And the higher temperature shows the after burned of the fuel.

8. Conclusion and Recommendation:

1. Objectives: The activity aims to demonstrate how to determine the calorific value of different types of fuel.

Answer: In this experiment we perform and learned how to compute and balance about the fuel being burn inside the bomb calorimeter. By the use of the formulas and ideal in our subject internal combustion engine.

2. Intended Learning Outcomes (ILOs):

The students shall be able to:

2.1 Perform the procedure of operating an oxygen bomb calorimeter.

In Performing the procedure of an oxygen bomb calorimeter, we can say it is patiently to perform because it has a lot of procedure to make before we can determine the higher heating value of the fuel. It needs a team work and follow the proper procedure to do the experiment and make a result.

2.2 Determine the calorific value of different types of fuel.

In this experiment, we only determine one type of fuel or acid of calorific value which is benzoic acid. We determine the calorific value by measuring the temperature of the water. Measuring the temperature of the water before and after burst are the given to calculate the result of a burning fuel.

2.3 Develop professional work ethics, including precision, neatness, safety and ability to follow instruction.

2.3.1 Duties and Responsibility of a Leader. (Zafra, Charles Jourdan M.)

As a Leader, I always assure that my group mates have their designated task and discuss them what they task. I listen to my instructor so we can perform our experiment right, and to avoid accident. Before we start the experiment I read the procedures the things we must do.

2.3.2 Duties and Responsibility of a Safety Officer. (Caringal, John Martin U.)

As a safety officer, The operator must be aware of safety precautions to prevent physical injury. Any pressure-containing device can explode, rupture, or discharge its contents if it is over pressurized. Take all necessary measures to avoid over-pressurization. Operating, installing, or maintaining the unit in any way that is not covered in this manual could cause death, serious personal injury, or damage to the equipment. This includes any modification to the equipment or use of parts not provided by ITT. If there is a question regarding the intended use of the equipment, please contact an ITT representative before proceeding. This manual clearly identifies accepted methods for disassembling units. These methods must be adhered to. Trapped liquid can rapidly expand and result in a violent explosion and injury. Never apply heat to impellers, propellers, or their retaining devices to aid in their removal unless explicitly stated in this manual. If the pump/motor is damaged or leaking, do not operate as it may cause an electric shock, fire, and explosion, liberation of toxic fumes, physical harm, or environmental damage. Correct/repair the problem prior to putting back in service. Do not change the service application without the approval of an authorized ITT representative.

2.3.3 Duties and Responsibility of a Quality Control Officer. (Macapagal,Roel U.)

As a quality inspector, I am responsible for the accuracy of the data in order to acquire low percentage error. I monitor the performers on their process on how they conduct the experiment. I also compute the actual data to make sure that the computations are correct.

3. Based on Observation:

During we perform the activity we can say that the temperature difference after and before we turning on the machine is very little almost no difference so we say that the amount of the fuel being burn is too small and the amount of water inside the bomb calorimeter is too big thats why the heat transfer of the fuel is very small, we suggest that the amount of the fuel put inside the bomb calorimeter must increase so that the temperature will also increase and the data being gathered is more precise and accurate.

Group Pictures:

Fig.1. Pouring the water in the bomb calorimeter. Fig.2. Preparing the fuel (Benzoic Acid).

Fig.3. Measuring the initial temp. of the water. Fig.4. Starting to burn the fuel.

Fig.5. Temp. result after burnt. Fig.6. Opening the vessel after the experiment.

a.b.

Result of the experiment:Fig.a. The crucible.Fig.b. The inside vessel.

9. Assessment Rubric:

T I P - V P A A 0 5 4 D Revision Status/Date:0/2009 September 09TECHNOLOGICAL INSTITUTE OF THE PHILIPPINESRUBRIC FOR LABORATORY PERFORMANCECRITERIABEGINNER1ACCEPTABLE2PROFICIENT3SCORE

Laboratory Skills

Manipulative SkillsMembers do not demonstrate needed skills.Members occasionally demonstrate needed skills.Members always demonstrate needed skills.

Experimental Set-upMembers are unable to set-up the materials.Members are able to set-up the materials with supervision.Members are able to set-up the material with minimum supervision.

Process SkillsMembers do not demonstrate targeted process skills.Members occasionally demonstrate targeted process skills.Members always demonstrate targeted process skills.

Safety PrecautionsMembers do not follow safety precautions.Members follow safety precautions most of the time.Members follow safety precautions at all times.

Work Habits

Time Management/Conduct of ExperimentMembers do not finish on time with incomplete data. Members finish on time with incomplete data.Members finish ahead of time with complete data and time to revise data.

Cooperative and Teamwork Members do not know their tasks and have no defined responsibilities. Group conflicts have to be settled by the teacher.Members have defined responsibilities most of the time. Group conflicts are cooperatively managed most of the time.Members are on tasks and have responsibilities at all times. Group conflicts are cooperatively managed at all times.

Neatness and OrderlinessMessy workplace during and after the experiment.Clean and orderly workplace with occasional mess during and after the experiment.Clean and orderly workplace at all times during and after the experiment.

Ability to do independent workMembers require supervision by the teacher.Members require occasional supervision by the teacher.Members do not need to be supervised by the teacher.

Other Comments/Observations:TOTAL SCORE

RATING= x 100%