Lab2

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Apr 3, 2024

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Bomb Calorimeter ME 495: Mechanical and Thermal Systems Lab Section 05: Thursday Group D Authors: Soeung Khanitha, Smith Emilee, Sichantha Jack, Taylor Charles Instructor: Dr. Hamid Nourollahi Experiment Performed, Date: Thursday, Mar 21, 2024 Lab Report Due Date: Thursday, Mar 28, 2024

1 Table of Contents Objective of Experiment ( ) ............................................................................................................................ 3 Equations and Symbols ( ) ............................................................................................................................. 3 Equipment ( ) .................................................................................................................................................. 3 Experimental Setup ( ) ................................................................................................................................... 3 Experimental Procedure ( ) ............................................................................................................................ 3 Experimental Results ( ) ................................................................................................................................. 3 Discussion of Results ( ) ................................................................................................................................ 3 Conclusion ( ) ................................................................................................................................................. 3 References ( Khanitha Soeung ) ..................................................................................................................... 3 List of Figures Table 1: Symbols .......................................................................................................... 3 List of Tables Table 1: Symbols .......................................................................................................... 3

2 Objective of Experiment (Emilee Smith, ) Using a Bomb Calorimeter, the heating value, or HV, of solid and liquid fuel can be found. The heating value is a measurement of the energy that a fuel produces. To determine the HV of a fuel, the bomb calorimeter burns a given fuel sample which will then transfer heat to the water surrounding the device. Based on the weight of the fuel and the temperature change, the heating value can be calculated. *Theory/Principle * Hypothesis Equations and Symbols (Emilee Smith) Equation 1: Heating Value (Energy Released) 𝐻? = ∆? 𝑤𝑎??? ? ???? = (?𝐶 ? ∆?) 𝑤𝑎??? ? ???? Equation 2: Heating Value (Complications) 𝐻? = [(?*𝐶 ? ∆? ?𝑜??????? ) 𝑤𝑎??? −(∆? 𝑤𝑖?? 𝐻? 𝑤𝑖?? )] ? ???? Table 1: Symbols Symbol Definition (g) ? ???? Mass of Fuel 𝐶 ? Specific Heat Capacity ∆? 𝑤𝑎??? (g) ? 𝑤𝑖?? Mass of Wire 𝐻? Heating Value ∆? Temperature Change Equipment ( ) Bomb Calorimeter

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3 ● A rigid Precision Scale: ● Oxygen Bottle: ● Experimental Procedure (Emilee Smith) The first step is to cut 10 cm of fuse wire and record the weight. Next, attach the wire between the leads of the bomb calorimeter (through small holes and twist access wire around lead). Slide the covers/clamps over the wire on each lead. It is important to make sure the fuse wire does not short circuit as this will prevent any heating and igniting of the fuel. Tare a clean fuel cup, then put a pellet of benzoic acid into the cup and record the weight. For the second trial, tare the fuel cup on the scale and measure around 0.75 g to 0.85 g of diesel fuel. (Since fuel evaporates quickly, do this step quickly). Next, slowly lower the fuel cup and bomb cover into the bomb and screw the top. *If it is too loose, oxygen can leak out and if it is too tight, disassembly will be difficult. Keep the bomb upright so nothing spills. The Instructor or TA will need to do the next step. They will add the Oxygen to the tank. Next, fill the stainless steel bucket with 2000 mL of water and then gently place the bomb calorimeter into the water. Record the initial temperature using the thermocouple provided. Attach ignition wires to the top of the vessel (they will be in water), then place the lid of the beige box on top. Insert the thermocouple through the hole of the lid and install the drive belt onto the motor and propeller. Temperature should be recorded every ten seconds on a table. Plug the ignition unit in and push the button when ready. The red light should light up momentarily which indicates that current is flowing. This is because the light is in series with the fuse wire. If it does not illuminate, there is a problem and the experiment will need to be restarted.

4 Record data every ten seconds until the temperature change remains constant. When this occurs, the run is finished. To disassemble the system, undo the drive belt, remove the lid, and then remove the bomb from the water bucket. Important: partially unscrew the vent valve to release pressure before unscrewing the bomb’s lid. Weigh whatever is leftover from the fuse wire and the fuel cup and record the values. Repeat this process using diesel fuel. When finished, clean and dry everything and record the heating value for the fuse wire. Experimental Results ( ) *Do we need graphs/tables of results? 1. Calculate the higher heating value using equation 2 and . ∆? ??𝑎????? Diesel fuel has a higher heating value of 36,709.40kJ/Kg, than the benzoic acid’s 17,565.39kJ/Kg. 2. Calculate the percent error versus the theoretical value of 46,446 kJ/kg for diesel fuel. %𝐸??𝑜? = | 𝑀?𝑎?????−?ℎ?𝑜???𝑖?𝑎? ?ℎ?𝑜???𝑖?𝑎? | * 100 = | 36,709.40−46,446 46,446 | * 100 = 20. 96%𝐸??𝑜? Discussion of Results ( Charles Taylor ) As shown within the Experimental Results the Diesel fuel has a greater higher heating value than the benzoic acid. These values were found using the equation shown in the sample calculations of the results sections. These calculations were done using an equation that takes into account the many complications of using a real system as opposed to a theoretical one. The first complication is that the heat generated by the combustion does not exclusively channel into the water it channels into many other parts of the system. These parts include but are not limited to the bucket and the bomb itself. Another complication is the fuse material burning alongside

5 the fuel in the calorimeter. This is fixed by measuring the fuse wire’s mass before and after the experiment. The third complication is heat losses due to the high temperatures of the calorimeter. Another complication is the state of the water (vapor or condensed) which is needed to determine the higher and lower bounds heating value, represented as LHV and HHV. The final possible complication is that the governing equation assumes the temperature rises in a uniform manner with the system’s boundary. These complications can and likely do lead directly to possible errors within our system. These complications would likely cause systematic error, however it is entirely possible that they cause some random errors as well. Some other random human errors that may occur in this experiment are a dirty weight cup affecting weight measurements, the experimenters not working quickly enough due to the rate of fuel evaporation, and the possibility that the pressure chamber is not fully sealed, in which case oxygen will likely leak out and affect heating data. Questions (Jack Sichantha, Charles Taylor ) 1. What is and how is it different from ? ? * ? 𝑤𝑎??? a. is the estimated mass of the water being heated. It’s different from ? * ? 𝑤𝑎??? because is calculated from the first part of the experiment. Since the heating ? * value of benzoic acid is 26.38 kJ/g, the mass of the water was calculated to be 3.00363kg. This is then used in calculating the heating valve for the diesel. 2. Compare the theoretical and actual heating values for diesel fuel. a. The heating value of diesel obtained from the experiment was 36,709.40 kJ/kg. The theoretical value given was 46,446 kJ/kg. The %error was calculated to be 20.96%.

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6 3. Is there any other possible explanation for a different HHV besides experimental error? (Hint: where did the theoretical value for the HHV come from?) a. The need to separate an HHV (and LHV) value from the normal heating value, HV is due to the nature of the water vapor produced by the burning of the hydrocarbon. This water vapor takes one of two forms depending on the temperature of the system, these forms are condensed or vapor. The HHV is calculated with the assumption that the water vapor produced entirely condenses. Alternatively the LHV assumes that the water vapor is not condensed when produced. Therefore a possible explanation for a different HHV besides experimental error would be that the water did not fully condense in the system, leaving us with some HV lower than the expected HHV. Conclusion ( ) References ( Khanitha Soeung ) Appendix ( )