DEPARTMENT OF CHEMICAL ENGINEERING & SUSTAINABILITY KULLIYYAH OF ENGINEERING BTEN 2182/CHEN 2182 SEMESTER 2, SESSION 2022/2023 CODE & NAME OF EXPERIMENT: HTL_E1: Heat Transfer by Conduction DATE OF LAB CLASS: 14.03.2023 GROUP NO: 3(b) No. Name Matric No. BTEN/CHEN Task 1. Ahmad Faruq bin Hisham 2015029 BTEN Safety Precaution, Discussion, Conclusion, 2. Amirul Azizi bin Mohamad Khairul Amri 2012349 BTEN Table content, List of table and figures, Abstract, Discussion 3. Nabilah Solehah binti Mohd Supian 2112762 CHEN Procedure, Result and Discussion 4. Nur Nisha Ismahani Binti Zamzuri 2119962 CHEN Introduction, Problem statement, Objective, Equipment TABLE OF CONTENT Abstract 3 1.0 Introduction and Theoretical Background 3 2.0 Problem Statement 4 3.0 Objectives 4 4.0 Equipment 5 5.0 Experimental Procedures/ Methodology 6 6.0 Results and Discussion 8 7.0 Conclusion 23 8.0 Safety and Precaution 23 References 24 1 LIST OF TABLE AND FIGURES Table 3.1A 8 Table 3.1B 9 Table 3.1C 10 Table 3.1D 11 Table 3.2B 14 Table 3.2C 17 Table 3.2D 20 Figure 1.1 5 Figure 2.1 7 Figure 3.1B 13 Figure 3.2B 15 Figure 3.1C 16 Figure 3.2C 17 Figure 3.1D 19 Figure 3.2D 21 2 ABSTRACT Heat conduction causes a temperature difference to exist between various body parts. In this experiment, heat is provided through calorimeters that are filled with both hot and cold water and flow through a rod made of copper and aluminium for heat conduction. The objective is to calculate and contrast the heat transfer coefficients of copper and aluminium in a gradient of constant temperature. The experiment will also look into the heat that is lost to the surroundings as a result of heat conduction in the rod. Firstly, part A was conducted by taking the temperature readings of hot water in the calorimeter every 10 seconds for 5 minutes. Based on the results, heat capacity is calculated. Then, water with temperature 0°C is used in part B to measure the temperature every minute for 30 minutes. This is to obtain the addition of the heat from the surroundings. Part C is performed to measure the heat transfer coefficient of copper rod and aluminium rod for part D. Each rod gives a different value of heat transfer coefficient. 1.0. INTRODUCTION AND THEORETICAL BACKGROUND Conduction Heat transfer is the movement of heat through matter such as gasses, liquids, or solids without the matter moving in bulk. Conduction, on the other hand, is the energy transfer within a substance from more energetic to less energetic particles as a result of particle interaction. The molecules collide and diffuse as they move randomly, which causes conduction heat transmission in gasses and liquids. On the other hand, heat transfer in solids occurs as a result of a combination of free electron energy transport and molecular lattice vibrations. The mode of heat transfer that takes place in a material due to a temperature gradient is called thermal conduction. Because of the superfluous convectional heat transfer that both liquids and gasses exhibit, a strong is used for pure conduction display. Heat conduction happens in three dimensions in real-world situations, a complexity that frequently necessitates computational analysis. The fundamental law that links rate of heat flow to temperature gradient and area must be demonstrated in the lab using a one-dimensional technique. For this lab report, there are 4 parts that have been conducted which is part A to measure heat capacity of the calorimeter by taking the temperature readings of hot water in the calorimeter every 10 seconds for 5 minutes. On the other hand, water with temperature 0°C is used to measure the heat capacity of calorimeter for part B by taking the temperature every minute for 30 minutes. Furthermore, part C is performed to measure the heat capacity of copper rod and aluminium rod for part D. 3 2.0. PROBLEM STATEMENT The main purposes of this experiment are to determine which material is the best heat conductor and to study the effects of the environment to the heat transfer in rod by conduction. As in our daily life application, we use materials with a high thermal conductivity that can effectively transfer heat such as kettle, cooker, etc. and readily take up heat from their environment. Poor thermal conductors resist heat flow such as thermos, ice box cooler, etc. and obtain heat slowly from their surroundings. By performing the experiment and undergoing some calculations, it is proved that copper rod is the best heat conductor compared to aluminum rod. When nearby molecules meet, conduction occurs, where energy is transferred from the more energetic to the less energetic molecules. Heat moves in the direction of falling temperatures since molecular energy increases with temperature. Thus, the rod temperature will change by time whether it decreases or increases because the heat is transferred to or from the environment by conduction. This experiment is very crucial especially for industries where they need to choose the best heat conductor materials in order to save the cost for the heat and energy production. 3.0. OBJECTIVES The objectives of these experiments are to measure and compare the heat transfer coefficient of copper and aluminium and to investigate how the heat losses to the environment during the heat conduction in rod. This experiment also undergoes some calculation by the data collected during the lab session to determine and prove which material is the best conductor. By performing this experiment, the students will get a better understanding and visualization of heat conduction and the effects from the environment. 4 4.0 EQUIPMENT Figure 1.1 5 5.0 PROCEDURE 6 Figure 2.1 7 6.0 RESULT & DISCUSSIONS 8 9 10 11 DISCUSSION PART A 1. Using this formula, the heat capacity of the Calorimeter is calculated based on the data of parameters obtained. πΆ = ππ€. ππ€. ππ€ – ππ ππ – πR Where cw = Specific heat capacity of water mw = Mass of the water ϑW = Temperature of the hot water ϑM = Mixing temperature ϑR = Room temperature At T= 300 s, and ππ= 77.8β, C = (4184 J⋅kg−1⋅β−1) (0.26 kg) (100β - 77.8β ) / ( 77.8β - 25.5β) = 461.76 J. β 12 PART B 1. From equation (6); βπ¬ =(πΆπ.ππ+πΆ).βπ where βT=T-T0, (T0= Temperature at time t = 0) βπ¬ = ( (4184 J⋅kg−1⋅β−1) (0.26 kg) + 461.76 J. β ) (10β ) = 15496 J 2. Graph temperature vs time for the cold water: Figure 3.1B 13 3. Graph heat from surrounding (Q) vs time Time (mins) Temperature (β) Heat (Q) (J) Time (mins) Temperature (β) Heat (Q) (J) 0 0 17572.8 16 6.7 5799.0 1 2.4 13355.3 17 7.0 5271.8 2 3.0 12300.96 18 7.2 4920.4 3 3.7 11070.9 19 7.5 4393.2 4 4.1 10368.0 20 7.7 4041.7 5 4.4 9840.8 21 7.9 3690.3 6 4.6 9489.3 22 8.2 3163.1 7 4.7 9313.6 23 8.4 2811.6 8 4.8 9137.9 24 8.6 2460.2 9 4.9 8962.1 25 8.9 1933.0 10 5.1 8610.7 26 9.1 1581.6 11 5.4 8083.5 27 9.3 1230.1 12 5.6 7732.0 28 9.5 878.6 13 5.9 7204.8 29 9.8 351.5 14 6.2 6677.7 30 10.0 0 15 6.4 6326.2 Table 3.2B By using equation Q = mCΔT we can find the value of heat from surrounding At t=0 Q= 0.42 kg ( 4184 J⋅kg−1⋅β−1 ) (10-0)β = 17572.8 J 14 We will find all value of heat for the other 30 minutes by using the above formula. The result is tabulated in the table above. Figure 3.2B 4. Slope for the graph is calculated: ππ/ ππ‘ = 4041.7−6326.2 20−15 π½ = -456.9 πππ 15 PART C 1. Using equation (6), the heat energy supplied to the lower calorimeter is calculated. At T= 300 s, ΔQ = ( (4184 J⋅kg−1⋅β−1) (0.26 kg) + 461.76 J. β) ) (2.96β) = 4586.82 J 2. Then, values and the change in the temperature difference metal rod plotted vs time. Figure 3.1C 3. After that, Q ambient+metal calculated using Equation (6) and plotted vs time. At T= 0, ΔT= 0.05 β, ΔQ = ( (4184 J⋅kg−1⋅β−1) (0.42 kg) + 461.76 J. β) ) (0.25β) = 554.76 J Then, Q ambient+metal calculated and tabled for the rest of 300 s. 16 Time (s) ΔT (β) ΔQ (J) 0 0.05 110.952 30 0.30 665.712 60 0.88 1952.76 90 1.55 3439.51 120 1.95 4327.13 150 2.32 5148.17 180 2.52 5591.98 210 2.85 6324.26 240 2.77 6146.74 270 2.94 6523.98 300 2.96 6568.36 Table 3.2C Figure 3.2C 17 4. Slope from the graph calculated to obtain dQ/dt ambient+metal dπ/ ππ‘ ambient+metal =685 J/s. 5. Heat transfer coefficient, λA calculated using Equation (1) and the values of dQ/dt metal. ππ/ ππ‘ = −ππ΄. ππ/ πX Where ππ/ ππ‘= The quantity of heat transported with time π= Heat conductivity of the substance A= Cross-sectional area ππ/ πX= Temperature gradient perpendicular to the surface Using Equation (4), T(x) = (T2-T1) / l T(x) = 275.96 K/ 0.315 m (685 J/s) = -π (4.91x10−4 m2 ) (876.06 K/m) π = -1592.48 W/m.K 6. Lastly, experimental value of πA compared with theoretical value for heat transfer coefficient of copper. Theoretical value of heat conductivity, π for copper is -401 W/ m.K. Meanwhile, the experimental value of π for copper is -1592.48 W/ m.K. Therefore, Percentage error = -1592.48 - (-401) / -401 . 100% = 297.12% As shown in the calculation above, the difference between experimental and theoretical value of heat coefficient of copper, π, is large. This may be due to a major amount of heat lost to the surroundings as a result from a mistake in the experiment setup. For example, some of the lower exposed part of the copper rod may be exposed to air and is not fully immersed in the cold water. Other than that, there may be mistakes in taking measurements. 18 PART D Using equation (6), the heat energy supplied to the lower calorimeter is calculated. At T= 300 s, ΔT = 4.50 β ΔQ = ( (4184 J⋅kg−1⋅β−1) (0.26 kg) + 461.76 J. β) ) (4.50β) = 6973.2 J Then, values and the change in the temperature difference on the metal rod plotted vs time. Figure 3.1D Then, we will calculate the value of Q ambient+metal by using formula 6 At t = 0, ΔT = 0.25 Thus Q ambient+metal; ΔQ = ( (4184 J⋅kg−1⋅β−1) (0.42 kg) + 461.76 J. β) ) (0.25β) = 554.76 J 19 We will find all values of heat for the other 300 seconds by using the above formula. The result is tabulated in the table below. Time (s) ΔT (β) ΔQ (J) 0 0.25 554.76 30 0.85 1886.2 60 1.70 3772.4 90 2.34 5192.6 120 2.90 6435.2 150 3.29 7300.6 180 3.64 8077.3 210 3.96 8787.4 240 4.30 9541.9 270 4.50 9985.7 300 4.50 9985.7 Table 3.2D After that, Q ambient+metal calculated and plotted vs time. 20 Figure 3.2D From the graph we will get the slope which is ππ/ ππ‘ = 1886.2−554.76 30−0 π½ =44.38 π Lastly, heat transfer coefficient, λA calculated using Equation (1) and the values of dQ/dt metal. ππ/ ππ‘ = −ππ΄. ππ/ πX Where ππ/ ππ‘= The quantity of heat transported with time π= Heat conductivity of the substance A= Cross-sectional area ππ/ πX= Temperature gradient perpendicular to the surface 21 From equation (4) T(x) = 277.65 K/ 0.315 m From equation (1) π½ (44.38 π ) = -π (4.91x10−4 m2 ) ( 881.4K/m) π = -102.55 W/m.K Lastly, experimental value of πA is compared to the theoretical value for heat transfer coefficient of aluminium. Theoretical value of heat conductivity, π for copper is -247 W/ m.K. Meanwhile, the experimental value of π for aluminium is -102.55 W/ m.K. Therefore, Percentage error =-102.55 - (-247) /-247 . 100% = -58% As shown in the calculation above, the difference between experimental and theoretical value of heat coefficient of aluminium, π, is quite large. This may be due to a major amount of heat lost to the surroundings as a result from a mistake in the experiment setup. For example, some of the lower exposed part of the aluminium rod may be exposed to air and is not fully immersed in the cold water. Other than that, there may be mistakes in taking measurements. Despite the fact that both copper and aluminium are excellent heat conductors, copper has a higher thermal conductivity than aluminium. Copper has a thermal conductivity of about 400 W/mK, compared to about 200 W/mK for aluminium. Accordingly, copper is a better material choice than aluminium for applications requiring rapid heat dissipation, such as heat sinks, heat exchangers, and electrical wiring. Copper also transfers heat more effectively than aluminium. Copper has a higher thermal conductivity than aluminium, despite the fact that both metals are excellent heat conductors. In comparison to aluminium, which has a thermal conductivity of about 200 W/mK, copper has about 400 W/mK. 22 As a result, copper is a better material option than aluminium for uses like heat sinks, heat exchangers, and electrical wiring that require quick heat dissipation. Additionally, copper conducts heat more efficiently than aluminium. In conclusion, copper conducts heat more effectively than aluminium, making it a better choice for applications where effective heat dissipation is crucial. But aluminium is a lighter and more affordable substitute, making it a better option for applications where weight and price are more important factors. 7.0 CONCLUSION To conclude, the results and discussion stated above shows that the objective of the experiments, which is to calculate and compare the heat transfer coefficients of copper and aluminium in a constant temperature gradient, as well as investigating the heat losses to the atmosphere during the heat conduction in rods, has been achieved. The experiment shows that heat conduction happens when temperatures in separate parts of a body differ from one another. The heat conduction will flow in one direction only, from a location with higher temperature to a lower one. Some amount of heat is lost to the environment during heat conduction due to the differences in temperature of the conductor and air surrounding it. The amount of heat transferred in both copper rod and aluminium rod is shown to follow a temperature gradient. As shown in the calculation above, the value of π of copper rod is higher than aluminium rod, indicating that copper is a better heat conductor than aluminium. Thus, Copper is often the greatest metal option for thermal conductivity. However in some cases where some factors, such as price and weight, are crucial when selecting the right metal, aluminium is a better option than copper. 23 8.0 SAFETY PRECAUTION In this experiment, the mediums which provide and receive heat - hot water and cold water - during heat transfer are being controlled in order to accurately determine the amount of heat transfer of the copper rod and aluminium rod. Thus, a number of safety precautions must be followed so that there are no external variables that will affect the heat transfer process. The first one is to ensure that the thermometer doesn't touch the inner surface of the calorimeter when recording the temperature of water in order to avoid measurement errors. Next is to remove all ice before starting the timer for Part B and Part C of the experiment so that the ice will not affect (lowers) the temperature of cold water during the heat transfer process. Before beginning the Part C of the experiment, stir the ice water until the temperature is as close to 0°C as possible. Always remember to put the calorimeter under running tap water after finishing each part of the experiment to reset the calorimeter’s temperature back to room temperature. Lastly, in Part C of the experiment, make sure that the exposed lower part of the metal rods are fully immersed with cold water to minimize heat loss to the surrounding during the heat transfer process. References Incropera, F. P., DeWitt, D. P. (2002), Fundamentals of Heat and Mass Transfer, John Wiley & Sons, Inc. (Chapter 2-5) Mokhena, T. C., Mochane, M. J., Sefadi, J. S., Motloung, S. V., & Andala, D. M. (2018). Thermal Conductivity of Graphite-Based Polymer Composites. Impact of Thermal Conductivity on Energy Technologies. doi:10.5772/intechopen.75676 Uswah Solehah Sh. (2020, July 12). Experiment 4A and 4B - Heat Capacity of Calorimeter & Ambient Heat [Video]. Youtube. https://www.youtube.com/watch?v=AQJG6XwDsSQ Uswah Solehah Sh. (2020, July 12). Experiment 4C and 4D - Thermal & Electrical Conductivity of Metal Rods [Video]. Youtube. https://www.youtube.com/watch?v=RAAzFHRU0fI 24 Wilson Power Solutions. (n.d.). Retrieved March 21, 2023, from https://www.wilsonpowersolutions.co.uk/app/uploads/WPS_Aluminium-v-Copper_white-paper_ -2021.pdf 25