EXPERIMENT MODULE CHEMICAL ENGINEERING EDUCATION LABORATORY GAS GAS HEAT EXCHANGER (HXG)

Transcription

1 EXPERIMENT MODULE EDUCATION LABORATORY GAS GAS HEAT EXCHANGER FACULTY OF INDUSTRIAL TECHNOLOGY INSTITUT TEKNOLOGI BANDUNG 2018

2 Kontributor: Dr. Dendy Adityawarman, Pri Januar Gusnawan, S.T., M.T., Dr. Ardiyan Harimawan, Ibrahim A. Suryawijaya, Corelya Erindah A., Darien Theodric HXG 2016/PW 2

3 TABLE OF CONTENTS TABLE OF CONTENTS... 3 LIST OF FIGURES... 4 LIST OF TABLES... 5 CHAPTER I PREFACE... 6 CHAPTER II EXPERIMENT GOALS AND OBJECTIVES... 7 I. Goals... 7 II. Objectives... 7 CHAPTER III RANCANGAN PERCOBAAN... 8 I. Equipment Layout... 8 II. Supporting Equipments and Materials... 8 CHAPTER IV WORKING PROCEDURE... 9 I. Working Procedure... 9 II. Measurement Methods BIBLIOGRAPHY APPENDIX A RAW DATA TABLE APPENDIX B CALCULATION PROCEDURE APPENDIX C SPECIFICATION AND LITERATURE DATA I. Literature Data II. Equipment Specification HXG 2016/PW 3

4 LIST OF FIGURES Figure 1. HXG equipment layout Figure 2. Experiment procedure Figure 3. Correction factor for ΔT for cross-flow type of heat exchanger (McCabe, 1993) HXG 2016/PW 4

5 LIST OF TABLES Table 1. Flowrate calibration data Table 2. Data for determining τ value Table 3. Main experiment data Table 4. HXG equipment specification HXG 2016/PW 5

6 CHAPTER I PREFACE Heat transfer is one of the most decisive factors in the operation of a chemical plant. Quantitative solution of heat transfer problems are generally based on the energy balance and the estimated heat transfer rate. Heat transfer will occur when there is a temperature difference between two objects. The heat will move from a high-temperature object to a lower temperature object. Heat can move in 3 ways ie conduction, convection, and radiation. In the event of conduction, heat moves along the path without the need of the medium to move. The heat moves from one particle to another in the medium. Convection events occur when heat transfer is carried by fluid flow. Thermodynamically, convection is expressed as the enthalpy stream, not heat flow. In the event of radiation, energy travels through electromagnetic waves. There are several common heat exchangers used in industry. These heat exchangers include double pipe, shell and tube, plate-frame, spiral, and lamella. The plate and frame type heat exchanger was developed in the late 1950s. Many researches have been done on this type of heat exchanger. Generally, water is used as the operating fluid. In this lab, the fluid used is air. Air is used as an operating fluid in an effort to optimize the heat carried by flue gas from a plant's operation. This practicum is also one of the more in-depth review efforts on flue gas. The result of practicum expected to be correlation between Reynolds number with Nusselt number. HXG 2016/PW 6

7 CHAPTER II EXPERIMENT GOALS AND OBJECTIVES I. Goals The goal of this practicum is to: 1. Learn the phenomena of heat transfer through plate and frame heat exchanger practicum. 2. Make students be able to choose the best heat transfer configuration. II. Objectives In the end of this practicum, students are expected to: 1. Determine overall heat transfer coefficient for variations of flowrate, inlet temperature, flow direction, and fluid placement. 2. Determine empiric heat transfer coefficient. 3. Obtain a configuration which gives the the best heat transfer coefficient. 4. Find correlation between Reynold and Nusselt Number. HXG 2016/PW 7

8 CHAPTER III RANCANGAN PERCOBAAN I. Equipment Layout Udara dingin keluar Udara panas keluar HE Plate and Frame Udara panas masuk Heater Udara dingin masuk Valve aliran dingin Valve aliran panas Udara lingkungan Blower Valve by-pass Udara by-pass Figure 1. HXG equipment layout. II. Supporting Equipments and Materials a. Measurement Tools 1. Thermocouple 2. Wet test meter 3. Manometer 4. Laptop (software: Labview) 5. Stopwatch b. Material Air HXG 2016/PW 8

9 I. Working Procedure CHAPTER IV WORKING PROCEDURE Procedure in conducting the experiment is shown by Figure 2.. Start Calibration of hot/cold air flowrate using wet-test meter Determining value of Experiment I using countercurrent plate with cold/hot flowrate variation Experiment I using countercurrent plate with cold/hot flowrate variation Determination of heat transfer characteristics (Q, U, h, Re, Nu) Data processing and analysis End Figure 2. Experiment procedure. HXG 2016/PW 9

10 II. Measurement Methods The experimental parameters were obtained from thermocouples mounted on the inlet/outlet stream of the hot and cold fluid. The measurement of experimental variables is obtained from fluid flow rate measurement using calibrated flowmeter. Calibration is done by using wet-test meter. Observed parameters are: 1. Flue gas inlet temperature (T h,i ) 2. Flue gas outlet temperature (T h,o ) 3. Cold air inlet temperature (T c,i ) 4. Cold air outlet temperature (T c,o ) 5. Flue gas inlet wall temperature (T wh,i ) 6. Flue gas outlet wall temperature (T wh,o ) 7. Cold air inlet wall temperature (T wc,i ) 8. Cold air outlet wall temperature (T wc,o ) Variables used in the experiment are flue gas flowrate and cold air flow rate. HXG 2016/PW 10

11 BIBLIOGRAPHY Mc Cabe, W.L., Unit Operation of Chemical Engineering, 5 rd Edition, McGraw-Hill Book Co., Singapore, 1993, pp Brown, G.G., Unit Operatons, Charles E. Tutle Co., Tokyo, 1960, pp Perry, R., Green, D.W., and Maloney, J.O., Perry s Chemical Engineers Handbook, 6th Edition, McGraw-Hill, Japan, 1984, Section 11 pp to HXG 2016/PW 11

12 APPENDIX A RAW DATA TABLE The data obtained from this experiment are divided into three steps: 6. Calibration data of flowrate Table 1. Flowrate calibration data. h (cm) V (L) t (s) 2. Determining τ value Table 2. Data for determining τ value. t (s) T ( o C) 3. Main Experiment Data Table 3. Main experiment data. h, cold h, hot Th,I ( o C) Th,o ( o C) Tc,i ( o C) Tc,o ( o C) Twh,i ( o C) Twh,o ( o C) Twc,i ( o C) Twc,o ( o C) HXG 2016/PW 12

13 APPENDIX B CALCULATION PROCEDURE B.1 Heat Transfer Rate (Q) The heat transfer rate of hot fluid and cold fluid is calculated using below formula. qhot = mhot. cphot. (Thot,in Thot,out) qcold = mcold. cpcold. (Tcold,in Tcold,out) B.2 Calculating q loss Heat dissipated to surroundings is shown as qloss. q q The value of thermal conductivity, thickness, and cross-sectional area of kaowool is obtained from literature. B.3. Calculating Heat Transfer Rate of Operation (q, operation ) q operation for each fluid is shown below. qoperasi,hot = qhot qloss qoperasi,cold = qcold qloss B.4. Calculating ΔT lmtd for Cross-Flow and Counter-Current Flow Heat Exchanger The temperature difference used is called log mean temperature difference, which is calculated using below formula: Equation above can only be used for counter-current flow heat exchanger. Above equation can be used for cross-flow type of heat exchanger by multiplying it with correction factor. Tlmtd,crossflow = Tlmtd,countercurrent. F ore si HXG 2016/PW 13

14 To find the correction factor from above graph, the value of Z and ɳ need to be calculated first using below formulas. The correction factor is obtained from Figure 12. Figure 3. Correction factor for ΔT for cross-flow type of heat exchanger (McCabe, 1993). B.5 Calculating Overall Heat Transfer Coefficient (U) Overall heat transfer coefficient can be calculated using two methods: empiric and theoretic. Theoretic overall heat transfer coefficient is calculated using following formula: x k h h h c : plate wall thickness : thermal conductivity of material : convective heat transfer coefficient of hot fluid : convective heat transfer coefficient of cold fluid Empiric overall heat transfer coefficient is determined using below formula: HXG 2016/PW 14

15 B.6 Determining Convective Heat Transfer Coefficient (h) The convective heat transfer coefficient is determined by using following formula: The temperature difference used in the calculation is called log mean temperature difference, which stands for the difference between the temperature of fluid and temperature of heat exchanger wall. B.7 Calculating Nusselt Number and Reynold Number The Reynold number is determined using following formula: h : convective heat transfer coefficient D : Plate equivalent diameter k : fluid thermal conductivity The Reynold number is determined using following formula: HXG 2016/PW 15

16 ρ : fluid density v : fluid flowrate µ : fluid viscosity D : diameter B.8 Determining the Correlation between Nusselt Number and Reynold Number Mathematically, the goal of this experiment is to find the value of a and b in below equation: Nu = a Re b The values of constant a and b can be determined from the regression between ln Nusselt and ln Reynold. From the experiment result, two plots were obtained for: 1) Nusselt number for hot fluid to Reynolds number, 2) Nusselt number for cold fluid to Reynolds number. B.9 Calculating the Efficiency of Heat Exchange The degree of heat exchange is shown through heat transfer efficiency which is shown by the formula below: HXG 2016/PW 16

17 I. Literature Data APPENDIX C SPECIFICATION AND LITERATURE DATA Literature data needed for data processing in HXG practicum module are: 1. Fluid density as a function of temperature 2. Fluid heat capacity (Cp) as a function of temperature 3. Fluid viscosity as a function of temperature 4. Fluid conductivity as a function of temperature 5. Specification of heat exchanger shown by Table 4. II. Equipment Specification Table 4. HXG equipment specification. Unit Counter-current Cross-current Note Jacket (kaowool) Conductivity k W/m.K 0,029 0,029 cotton Cross-sectional A m 2 0,1443 0,1439 area Thickness x m 0,017 0,017 Plate Conductivity k W/m.K iron steel, carbon 1% Cross-sectional A m 2 0,0585 0,05846 area Plate thickness x m 0,005 0,005 Pipe Diameter de m 0, ,02804 HXG 2016/PW 17

18 JOB SAFETY ANALYSIS No Materials Properties Countermeasures 1 Air (79% N 2, 21% Odorless Gas Melting point of -216,2 o C (10 No specific countermeasures needed. O 2 ) Colorless Not toxic psig) Density of 1,2 Leakage of hot gas is hazardous. If that Not hazardous kg/m 3 (1 atm) happens, quickly identify point of leakage and close the leakage. Avoid direct contact with body Accidents that may happen Short circuit connection due to electricity contact with water Countermeasures Try to cut the electrical connection on equipments. If not possible, contact authorities. Slip caused by water puddle from leakage of hose/pipe connection. Valve or handle broken. Make sure all hose/pipe connections are properly assembled to prevent leakage. Clean water spill immediately. Make sure the direction of rotation of connection is correct. Try to open valve slowly to prevent breaking valve. If broken, change the valve with the new one or contact authorities. Safety gear Gloves Labcoat Mask Goggle Asisten Pembimbing Koordinator Lab TK HXG 2016/PW 18