Overall Heat Transfer Coefficient
|
|
- Barnaby Brown
- 5 years ago
- Views:
Transcription
1
2 Overall Heat Transfer Coefficient A heat exchanger typically involves two flowing fluids separated by a solid wall. Heat is first transferred from the hot fluid to the wall by convection, through the wall by conduction, and from the wall to the cold fluid again by convection. Any radiation effects are usually included in the convection heat transfer coefficients. 2
3 For tubular heat exchangers we must take into account the conduction resistance in the wall and convection resistances of the fluids at the inner and outer tube surfaces. 1 UA Overall Heat Transfer Coefficient 1 h A i i ln( Do / Di ) 2 kl 1 h A o o The A i is the area of the inner surface of the wall that separates the two fluids, and A o is the area of the outer surface of the wall. In other words, A i and A o are surface areas of the separating wall wetted by the inner and the outer fluids, respectively. When one fluid flows inside a circular tube and the other outside of it, we have: Note that: 1 UA 1 U A i i o A A 1 U A i o o D L i D o L where inner tube surface where outer tube surface 3
4 Overall Heat Transfer Coefficient Then Eq. for the overall heat transfer coefficient simplifies to where U U i U o. hi and ho are the individual convection heat transfer coefficients inside and outside the tube,
5 Overall Heat Transfer Coefficient 5
6 Fouling
7 Fouling The performance of heat exchangers usually deteriorates with time as a result of accumulation of deposits on heat transfer surfaces. The layer of deposits represents additional resistance to heat transfer and causes the rate of heat transfer in a heat exchanger to decrease. The net effect of these accumulations on heat transfer is represented by a Fouling factor, R f. The overall heat transfer coefficient can be written: 1 UA h i 1 A i R " " f i R, ln( Do / Di ) f, o i 2 kl A o A h o 1 A o 7
8 Fouling Some values of fouling factors are given here. More comprehensive tables of fouling factors are available in handbooks. As you would expect, considerable uncertainty exists in these values, and they should be used as a guide in the selection and evaluation of heat exchangers to account for the effects of anticipated fouling on heat transfer. 8
9 9
10 Schematic 10
11 11
12 Schematic 12
13 Schematic 13
14 Use of a Correction Factor Multipass and Cross-Flow Heat Exchangers The log mean temperature difference ΔT lm relation developed earlier is limited to parallel-flow and counter-flow heat exchangers only. In such cases, it is convenient to relate the equivalent temperature difference to the log mean temperature difference relation for the counter-flow case as: where F is the correction factor, which depends on the geometry of the heat exchanger and the inlet and outlet temperatures of the hot and cold fluid streams. The ΔT lm,cf is the log mean temperature difference for the case of a counterflow heat exchanger with the same inlet and outlet temperatures and is determined from the above equation, and by taking: ΔT 1 = T h,in T c,out and ΔT 2 = T h,out T c,in as shown in the figure.
15 Multipass and Cross-Flow Heat Exchangers where the subscripts 1 and 2 represent the inlet and outlet, respectively. Note that for a shell-and-tube heat exchanger, T and t represent the shell- and tube-side temperatures, respectively, as shown in the correction factor charts.
16
17 Example (3) : Cross Flow Heat exchangers Cross flow heat exchanger Heat Exchangers 17
18 Heat Exchangers 18
19 Example (4) Investigate the heat-transfer performance of the HEX in example 3 if the oil flow rate is reduced in half while the steam flow remains same. Assume U remains constant at 275 W/m 2. C 19
20 Q= mcp (t2 15) = m Cp (130 T1) (a) Q = U A T LMTD F (b) This why there was a need for another easier method Effective-Ntu method 20
21 Multipass and Cross-Flow Heat Exchangers
22 Multipass and Cross-Flow Heat Exchangers FIGURE Correction factor F charts for common shell-and-tube and cross-flow heat exchangers
23
24 Schematic
25 Schematic
26 Schematic
27 Schematic
28 Schematic
29 Schematic
30 Schematic
31 Schematic
32 Schematic
33 THE EFFECTIVENESS NTU METHOD Once ΔT lm, the mass flow rates, and the overall heat transfer coefficient (U) are available, the heat transfer surface area of the heat exchanger can be determined from Therefore, the LMTD method is very suitable for determining the size of a heat exchanger to realize prescribed outlet temperatures when the mass flow rates and the inlet and outlet temperatures of the hot and cold fluids are specified. With the LMTD method, the task is to select a heat exchanger that will meet the prescribed heat transfer requirements. The procedure to be followed by the selection process is: 1. Select the type of heat exchanger suitable for the application. 2. Determine any unknown inlet or outlet temperature and the heat transfer rate using an energy balance. 3. Calculate the log mean temperature difference ΔT lm and the correction factor F, if necessary. 4. Obtain (select or calculate) the value of the overall heat transfer coefficient U. 5. Calculate the heat transfer surface area A s.
34 THE EFFECTIVENESS NTU METHOD NTU Number of Transfer Units This method is based on a dimensionless parameter called the heat transfer effectiveness ε, defined as: The actual heat transfer rate in a heat exchanger can be determined from an energy balance on the hot or cold fluids and can be expressed as: To determine the maximum possible heat transfer rate in a heat exchanger, we first recognize that the maximum temperature difference: the maximum possible heat transfer rate in a heat exchanger is: where C min is the smaller of C h =ṁ h C Ph and C C = m C C pc
35 (ε) NTU Number of Transfer Units Consider two counter-flow heat exchangers, one in which the cold fluid has the larger ΔT (smaller m cp) and a second in which the cold fluid has the smaller ΔT (larger m cp): The effectiveness is the ratio of the energy recovered in a HX to that recoverable in an ideal HX. Note that the use of the upper case T in the numerator, in contrast to our normal terminology, does not indicate that the hot fluid temperature change is used here.
36 Example: Double pipe heat exchanger Water at the rate of 68 kg/min is heated from 35 to 75 C by an oil having a specific heat of 1.9 kj/kg. C. The fluids are used in counterflow double pipe heat exchanger, and the oil enters the exchanger at 110 C and leaves at 75 C. The overall heat-transfer coefficient is 320 W/m 2. C. Calculate the heat exchanger area. Solution: The total heat transfer is determined from the energy absorbed by the water. Since all the fluid temperatures are known, the LMTD can be calculated by using the temperature scheme. T lm To Ti ln( T / T ) o i From the expression: 36
37 Continue Example (1) : (1:2) Shell & Tube heat exchanger, knowing that water is in the shell side and oil is in the tube side, recalculate the needed area..?? = (75-110)/(35-110) = = (35-75)/(75-110) = Heat Exchangers 37
38 Example A thin-walled concentric tube heat exchanger of 0.19-m length is to be used to heat deionized water from 40 to 60 C at a flow rate of 5 kg/s. the deionized water flows through the inner tube of 30-mm diameter while hot process water at 95 C flows in the annulus formed with the outer tube of 60- mm diameter. The thermo physical properties of the fluids are: Find: (1) minimum flow rate required for the hot process water, (b) required overall heat transfer coefficient and whether it is possible to accomplish this heating, and (c) for CF arrangements minimum process water flow required and the effectiveness?
39 Assumptions: (1) Negligible heat loss to surroundings. (2) Negligible kinetic and potential energy changes.
40
41 Example An automobile radiator may be viewed as a cross-flow heat exchanger with both fluids unmixed. Water, which has flow rate of 0.05kg/s, enters the radiator at 400K and is to leave at 330 K. The water is cooled by air which enters at 0.75kg/s and 300K. If the overall heat transfer coefficient is 200W/m 2.K, what is the required heat transfer surface area? Known: flow rate and inlet temperature for automobile radiator. Overall heat transfer coefficient. Find: Area required to achieve a prescribed outlet temperature. Schematic Assumptions: (1) Negligible heat loss to surroundings and kinetic and potential energy changes, (2) Constant properties.
42 Analysis: The required heat transfer rate is Using the ε-ntu method,
43 Example Water at 225 kg/h is to be heated from 35 to 95 C by means of a concentric tube heat exchanger. Oil at 225kg/h and 210 C, with a specific heat of 2095 J/kg.K, is to be used as the hot fluid, If the overall heat transfer coefficient based on the outer diameter of the inner tube if 550W/m 2.K, determine the length of the exchanger if the outer diameters is 100mm. Known: Concentric tube heat exchanger. Find: Length of the exchanger Schematic Assumptions: (1) Negligible heat loss to surroundings, (2) Negligible kinetic and potential energy changes, (3) Constant properties. The heat rate, q, can be evaluated from an energy balance on the cold fluid:
44
45 Example Consider a very long, concentric tube heat exchanger having hot and cold water inlet temperatures of 85 and 15 C. The flow rate of the hot water is twice that of the cold water. Assuming equivalent hot and cold water specifies heats; determine the hot water outlet temperature for the following modes of operation (a) Counter flow, (b) Parallel flow. Known: A very long, concentric tube heat exchanger having hot and cold water inlet temperatures of 85 and 15 C, respectively: flow rate of the hot water is twice that of the cold water. Find: outlet temperatures for counter flow and parallel flow operations. Schematic Assumptions: (1) equivalent hot and cold water specific heats, (2) Negligible Kinetic and potential energy changes, (3) No heat loss to surroundings.
46 Operating in the counter flow mode is: Substituting numerical values:
47
48
49 Schematic
50 Schematic
51 The determination of requires the availability of the inlet temperature of the hot and cold fluids and their mass flow rates, which are usually specified. Then, once the effectiveness of the heat exchanger is known, the actual heat transfer rate can be determined from: The below Equ developed before in previous lecture for a parallel-flow heat exchanger: can be rearranged as: Also, solving the following Eq. for T h,out Gives:
52 Then: which simplifies to: Eq We now manipulate the definition of effectiveness to obtain: Substituting this result into Eq and solving for e gives the following relation for the effectiveness of a parallel-flow heat exchanger: Taking either C c or C h to be C min (both approaches give the same result), the relation above can be expressed more conveniently as:
53 Effectiveness relations of the heat exchangers typically involve the dimensionless group U As /C min. This quantity is called the number of transfer units NTU and is expressed as: where U is the overall heat transfer coefficient and A s is the heat transfer surface area of the heat exchanger. NTU is a measure of the heat transfer surface area A s. Thus, the larger the NTU, the larger the heat exchanger. In heat exchanger analysis, it is also convenient to define another dimensionless quantity called the capacity ratio c as:
54 Effectiveness relations have been developed for a large number of heat exchangers, and the results are given in the Table below. The effectivenesses of some common types of heat exchangers are also plotted in the becoming figures
55
56
57
58 Some observations from the effectiveness relations and charts already given: 1. The value of the effectiveness ranges from 0 to 1. It increases rapidly with NTU for small values (up to about NTU 1.5) but rather slowly for larger values. Therefore, the use of a heat exchanger with a large NTU (usually larger than 3) and thus a large size cannot be justified economically, since a large increase in NTU in this case corresponds to a small increase in effectiveness. Thus, a heat exchanger with a very high effectiveness may be highly desirable from a heat transfer point of view but rather undesirable from an economical point of view. 2. For a given NTU and capacity ratio c = C min /C max, the counter-flow heat exchanger has the highest effectiveness, followed closely by the cross-flow heat exchangers with both fluids unmixed. As you might expect, the lowest effectiveness values are encountered in parallel-flow heat exchangers (Fig ).
59 3. The effectiveness of a heat exchanger is independent of the capacity ratio c for NTU values of less than about The value of the capacity ratio c ranges between 0 and 1. For a given NTU, the effectiveness becomes a maximum for c = 0 and a minimum for c =1. The case c = C min /C max 0 corresponds to C max, which is realized during a phase-change process in a condenser or boiler. condenser or boiler. All effectiveness relations in this case reduce to:
60 it can also be determined from the effectiveness NTU method by first evaluating the effectiveness ε from its definition and then the NTU from the appropriate NTU relation mentioned in the following Table.
61 Schematic
62 Schematic
63 Schematic
64 Schematic
65 Schematic
66 Number of Transfer Units (NTU) Recall that the energy flow in any HX is described by three equations: Δθ eff The effective temperature difference We may generalize the latter two expressions, using ε-ntu terminology as follows: If we eliminate Q between the HX equation and one of the 1st Law equations This expression may be made non-dimensional by taking the temperatures to one side and the other terms to the other side:
67
68
69
70
71
72 Capacity Ratio, C R The final non-dimensional ratio needed here is the capacity ratio, defined as follows:
73 SELECTION OF HEAT EXCHANGERS Heat exchangers are complicated devices, and the results obtained with the simplified approaches presented above should be used with care. The proper selection depends on several factors: 1. Heat Transfer Rate: A heat exchanger should be capable of transferring heat at the specified rate in order to achieve the desired temperature change of the fluid at the specified mass flow rate. 2. Cost: Budgetary limitations usually play an important role in the selection of heat exchangers, except for some specialized cases where money is no object. 3. Pumping Power: In a heat exchanger, both fluids are usually forced to flow by pumps or fans that consume electrical power. The annual cost of electricity associated with the operation of the pumps and fans can be determined from:
74 4. Size and Weight: SELECTION OF HEAT EXCHANGERS Normally, the smaller and the lighter the heat exchanger, the better it is. 5. Type: The type of heat exchanger to be selected depends primarily on the type of fluids involved, the size and weight limitations, and the presence of any phase change processes. 6. Materials: The materials used in the construction of the heat exchanger may be an important consideration in the selection of heat exchangers. For example, the thermal and structural stress effects need not be considered at pressures below 15 atm or temperatures below 150 C.
75 Schematic
76 Schematic
77 Schematic
INSTRUCTOR: PM DR MAZLAN ABDUL WAHID
SMJ 4463: HEAT TRANSFER INSTRUCTOR: PM DR MAZLAN ABDUL WAHID http://www.fkm.utm.my/~mazlan TEXT: Introduction to Heat Transfer by Incropera, DeWitt, Bergman, Lavine 5 th Edition, John Wiley and Sons DR
More informationChapter 11: Heat Exchangers. Dr Ali Jawarneh Department of Mechanical Engineering Hashemite University
Chapter 11: Heat Exchangers Dr Ali Jawarneh Department of Mechanical Engineering Hashemite University Objectives When you finish studying this chapter, you should be able to: Recognize numerous types of
More informationIntroduction to Heat and Mass Transfer
Introduction to Heat and Mass Transfer Week 16 Merry X mas! Happy New Year 2019! Final Exam When? Thursday, January 10th What time? 3:10-5 pm Where? 91203 What? Lecture materials from Week 1 to 16 (before
More informationT718. c Dr. Md. Zahurul Haq (BUET) HX: Energy Balance and LMTD ME 307 (2018) 2/ 21 T793
HX: Energy Balance and LMTD Dr. Md. Zahurul Haq Professor Department of Mechanical Engineering Bangladesh University of Engineering & Technology (BUET) Dhaka-000, Bangladesh http://zahurul.buet.ac.bd/
More informationc Dr. Md. Zahurul Haq (BUET) Heat Exchangers: Rating & Sizing - I ME 307 (2017) 2 / 32 T666
Heat Exchanger: Rating & Sizing Heat Exchangers: Rating & Sizing - I Dr. Md. Zahurul Haq Professor Department of Mechanical Engineering Bangladesh University of Engineering & Technology (BUET) Dhaka-000,
More informationPROBLEM The heat rate, q, can be evaluated from an energy balance on the cold fluid, 225 kg/h J. 3600s/h
PROBLEM 11.41 KNOWN: Concentric tube heat exchanger. FIND: Length of the exchanger. SCHEMATIC: ASSUMPTIONS: (1) Negligible heat loss to surroundings, () Negligible kinetic and potential energy changes,
More information23 1 TYPES OF HEAT EXCHANGERS
cen5426_ch23.qxd /26/04 9:42 AM Page 032 032 FUNDAMENTALS OF THERMAL-FLUID SCIENCES 23 TYPES OF HEAT EXCHANGERS Different heat transfer applications require different types of hardware different configurations
More informationMultiple pass and cross flow heat exchangers
Multiple pass and cross flow heat exchangers Parag Chaware Department of Mechanical Engineering of Engineering, Pune Multiple pass and cross flow heat exchangers Parag Chaware 1 / 13 Introduction In order
More informationINTRODUCTION: Shell and tube heat exchangers are one of the most common equipment found in all plants. How it works?
HEAT EXCHANGERS 1 INTRODUCTION: Shell and tube heat exchangers are one of the most common equipment found in all plants How it works? 2 WHAT ARE THEY USED FOR? Classification according to service. Heat
More informationHow can we use Fundamental Heat Transfer to understand real devices like heat exchangers?
Lectures 7+8 04 CM30 /30/05 CM30 Transport I Part II: Heat Transfer Applied Heat Transfer: Heat Exchanger Modeling, Sizing, and Design Professor Faith Morrison Department of Chemical Engineering Michigan
More informationApplied Heat Transfer:
Lectures 7+8 CM30 /6/06 CM30 Transport I Part II: Heat Transfer Applied Heat Transfer: Heat Exchanger Modeling, Sizing, and Design Professor Faith Morrison Department of Chemical Engineering Michigan Technological
More informationHEAT EXCHANGER. Objectives
HEAT EXCHANGER Heat exchange is an important unit operation that contributes to efficiency and safety of many processes. In this project you will evaluate performance of three different types of heat exchangers
More informationHeat Exchangers: Rating & Performance Parameters. Maximum Heat Transfer Rate, q max
Heat Exchangers: Rating & Performance Parameters Dr. Md. Zahurul Haq HTX Rating is concerned with the determination of the heat transfer rate, fluid outlet temperatures, and the pressure drop for an existing
More informationME 331 Homework Assignment #6
ME 33 Homework Assignment #6 Problem Statement: ater at 30 o C flows through a long.85 cm diameter tube at a mass flow rate of 0.020 kg/s. Find: The mean velocity (u m ), maximum velocity (u MAX ), and
More informationDesigning Steps for a Heat Exchanger ABSTRACT
Designing Steps for a Heat Exchanger Reetika Saxena M.Tech. Student in I.F.T.M. University, Moradabad Sanjay Yadav 2 Asst. Prof. in I.F.T.M. University, Moradabad ABSTRACT Distillation is a common method
More informationAnalyzing Mass and Heat Transfer Equipment
Analyzing Mass and Heat Transfer Equipment (MHE) Analyzing Mass and Heat Transfer Equipment Scaling up to solving problems using process equipment requires both continuum and macroscopic knowledge of transport,
More informationThermal Unit Operation (ChEg3113)
Thermal Unit Operation (ChEg3113) Lecture 3- Examples on problems having different heat transfer modes Instructor: Mr. Tedla Yeshitila (M.Sc.) Today Review Examples Multimode heat transfer Heat exchanger
More informationMemorial University of Newfoundland Faculty of Engineering and Applied Science
Memorial University of Newfoundl Faculty of Engineering Applied Science ENGI-7903, Mechanical Equipment, Spring 20 Assignment 2 Vad Talimi Attempt all questions. The assignment may be done individually
More informationPLATE & FRAME HEAT EXCHANGER
PLATE & FRAME HEAT EXCHANGER By Farhan Ahmad Department of Chemical Engineering, University of Engineering & Technology Lahore Introduction The plate heat exchanger (PHE) was first introduced by Dr Richard
More informationطراحی مبدل های حرارتی مهدي کریمی ترم بهار HEAT TRANSFER CALCULATIONS
طراحی مبدل های حرارتی مهدي کریمی ترم بهار 96-97 HEAT TRANSFER CALCULATIONS ١ TEMPERATURE DIFFERENCE For any transfer the driving force is needed General heat transfer equation : Q = U.A. T What T should
More informationDESIGN AND COST ANALYSIS OF HEAT TRANSFER EQUIPMENTS
DESIGN AND COST ANALYSIS OF HEAT TRANSFER EQUIPMENTS Md. Khairul Islam Lecturer Department of Applied Chemistry and Chemical Engineering. University of Rajshahi. What is design? Design includes all the
More informationLevel 7 Post Graduate Diploma in Engineering Heat and mass transfer
9210-221 Level 7 Post Graduate Diploma in Engineering Heat and mass transfer 0 You should have the following for this examination one answer book non programmable calculator pen, pencil, drawing instruments
More informationExamination Heat Transfer
Examination Heat Transfer code: 4B680 date: June 13, 2008 time: 14.00-17.00 Note: There are 4 questions in total. The first one consists of independent subquestions. If possible and necessary, guide numbers
More informationCHAPTER FOUR HEAT TRANSFER
CHAPTER FOUR HEAT TRANSFER 4.1. Determination of Overall Heat Transfer Coefficient in a Tubular Heat Exchanger 4.2. Determination of Overall Heat Transfer Coefficient in a Plate Type Heat Exchanger 4.3.
More informationExperimental Analysis of Double Pipe Heat Exchanger
206 IJEDR Volume 4, Issue 2 ISSN: 232-9939 Experimental Analysis of Double Pipe Heat Exchanger Urvin R. Patel, 2 Manish S. Maisuria, 3 Dhaval R. Patel, 4 Krunal P. Parmar,2,3,4 Assistant Professor,2,3,4
More informationPROBLEM and from Eq. 3.28, The convection coefficients can be estimated from appropriate correlations. Continued...
PROBLEM 11. KNOWN: Type-30 stainless tube with prescribed inner and outer diameters used in a cross-flow heat exchanger. Prescribed fouling factors and internal water flow conditions. FIND: (a) Overall
More informationThe Effect of Mass Flow Rate on the Effectiveness of Plate Heat Exchanger
The Effect of Mass Flow Rate on the of Plate Heat Exchanger Wasi ur rahman Department of Chemical Engineering, Zakir Husain College of Engineering and Technology, Aligarh Muslim University, Aligarh 222,
More information8.1 Technically Feasible Design of a Heat Exchanger
328 Technically Feasible Design Case Studies T 2 q 2 ρ 2 C p2 T F q ρ C p T q ρ C p T 2F q 2 ρ 2 C p2 Figure 3.5. Countercurrent double-pipe exchanger. 8. Technically Feasible Design of a Heat Exchanger
More informationIf there is convective heat transfer from outer surface to fluid maintained at T W.
Heat Transfer 1. What are the different modes of heat transfer? Explain with examples. 2. State Fourier s Law of heat conduction? Write some of their applications. 3. State the effect of variation of temperature
More informationLecture 3 Heat Exchangers
L3 Leture 3 Heat Exangers Heat Exangers. Heat Exangers Transfer eat from one fluid to anoter. Want to imise neessary ardware. Examples: boilers, ondensors, ar radiator, air-onditioning oils, uman body.
More informationBen Wolfe 11/3/14. Figure 1: Theoretical diagram showing the each step of heat loss.
Condenser Analysis Water Cooled Model: For this condenser design there will be a coil of stainless steel tubing suspended in a bath of cold water. The cold water will be stationary and begin at an ambient
More informationInvestigation of Heat Transfer on Smooth and Enhanced Tube in Heat Exchanger
International Journal of Current Engineering and Technology E-ISSN 2277 4106, P-ISSN 2347 5161 2015INPRESSCO, All Rights Reserved Available at http://inpressco.com/category/ijcet Research Article Investigation
More informationPrinciples of Food and Bioprocess Engineering (FS 231) Problems on Heat Transfer
Principles of Food and Bioprocess Engineering (FS 1) Problems on Heat Transfer 1. What is the thermal conductivity of a material 8 cm thick if the temperature at one end of the product is 0 C and the temperature
More informationTutorial 1. Where Nu=(hl/k); Reynolds number Re=(Vlρ/µ) and Prandtl number Pr=(µCp/k)
Tutorial 1 1. Explain in detail the mechanism of forced convection. Show by dimensional analysis (Rayleigh method) that data for forced convection may be correlated by an equation of the form Nu = φ (Re,
More informationLAMINAR FORCED CONVECTION HEAT TRANSFER IN HELICAL COILED TUBE HEAT EXCHANGERS
LAMINAR FORCED CONVECTION HEAT TRANSFER IN HELICAL COILED TUBE HEAT EXCHANGERS Hesam Mirgolbabaei ia, Hessam Taherian b a Khajenasir University of Technology, Department of Mechanical Engineering, Tehran,
More informationHow can we use Fundamental Heat Transfer to understand real devices like heat exchangers?
Lecture 7 03 CM30 /0/03 CM30 Transort I Part II: Heat Transfer Alied Heat Transfer: Heat Exchanger Modeling, Sizing, and Design Professor Faith Morrison Deartment of Chemical Engineering Michigan Technological
More informationHeat Transfer Predictions for Carbon Dioxide in Boiling Through Fundamental Modelling Implementing a Combination of Nusselt Number Correlations
Heat Transfer Predictions for Carbon Dioxide in Boiling Through Fundamental Modelling Implementing a Combination of Nusselt Number Correlations L. Makaum, P.v.Z. Venter and M. van Eldik Abstract Refrigerants
More informationANSI/AHRI Standard (Formerly ARI Standard ) 2006 Standard for Performance Rating of Desuperheater/Water Heaters
ANSI/AHRI Standard 470-2006 (Formerly ARI Standard 470-2006) 2006 Standard for Performance Rating of Desuperheater/Water Heaters IMPORTANT SAFETY DISCLAIMER AHRI does not set safety standards and does
More informationCoolant. Circuits Chip
1) A square isothermal chip is of width w=5 mm on a side and is mounted in a subtrate such that its side and back surfaces are well insulated, while the front surface is exposed to the flow of a coolant
More information4.1 Derivation and Boundary Conditions for Non-Nipped Interfaces
Chapter 4 Roller-Web Interface Finite Difference Model The end goal of this project is to allow the correct specification of a roller-heater system given a general set of customer requirements. Often the
More informationExamination Heat Transfer
Examination Heat Transfer code: 4B680 date: 17 january 2006 time: 14.00-17.00 hours NOTE: There are 4 questions in total. The first one consists of independent sub-questions. If necessary, guide numbers
More informationNumerical Analysis of Plate Heat Exchanger Performance in Co-Current Fluid Flow Configuration
Numerical Analysis of Plate Heat Exchanger Performance in Co-Current Fluid Flow Configuration H. Dardour, S. Mazouz, and A. Bellagi Abstract For many industrial applications plate heat exchangers are demonstrating
More informationTransfer processes: direct contact or indirect contact. Geometry of construction: tubes, plates, and extended surfaces
Chapter 5 Heat Exchangers 5.1 Introduction Heat exchangers are devices used to transfer heat between two or more fluid streams at different temperatures. Heat exchangers find widespread use in power generation,
More information1. Nusselt number and Biot number are computed in a similar manner (=hd/k). What are the differences between them? When and why are each of them used?
1. Nusselt number and Biot number are computed in a similar manner (=hd/k). What are the differences between them? When and why are each of them used?. During unsteady state heat transfer, can the temperature
More informationPhone: , For Educational Use. SOFTbank E-Book Center, Tehran. Fundamentals of Heat Transfer. René Reyes Mazzoco
8 Fundamentals of Heat Transfer René Reyes Mazzoco Universidad de las Américas Puebla, Cholula, Mexico 1 HEAT TRANSFER MECHANISMS 1.1 Conduction Conduction heat transfer is explained through the molecular
More informationGiven: Hot fluid oil, Cold fluid - water (T 1, T 2 ) (t 1, t 2 ) Water
. In a counter flow double pipe eat excanger, oil is cooled fro 85 to 55 by water entering at 5. Te ass flow rate of oil is 9,800 kg/ and specific eat f oil is 000 J/kg K. Te ass flow rate of water is
More informationNUMERICAL ANALYSIS OF PARALLEL FLOW HEAT EXCHANGER
NUMERICAL ANALYSIS OF PARALLEL FLOW HEAT EXCHANGER 1 Ajay Pagare, 2 Kamalnayan Tripathi, 3 Nitin Choudhary 1 Asst.Profesor at Indore institute of science and technology Indore, 2 Student at Indore institute
More informationHeat Exchanger Design
Heat Exchanger Design Heat Exchanger Design Methodology Design is an activity aimed at providing complete descriptions of an engineering system, part of a system, or just a single system component. These
More informationIn order to optimize the shell and coil heat exchanger design using the model presented in Chapter
1 CHAPTER FOUR The Detailed Model In order to optimize the shell and coil heat exchanger design using the model presented in Chapter 3, one would have to build several heat exchanger prototypes, and then
More informationSHRI RAMSWAROOP MEMORIAL COLLEGE OF ENGG. & MANAGEMENT B.Tech. [SEM V (ME-51, 52, 53, 54)] QUIZ TEST-1 (Session: )
QUIZ TEST-1 Time: 1 Hour HEAT AND MASS TRANSFER Note: All questions are compulsory. Q1) The inside temperature of a furnace wall ( k=1.35w/m.k), 200mm thick, is 1400 0 C. The heat transfer coefficient
More informationEstimating number of shells and determining the log mean temperature difference correction factor of shell and tube heat exchangers
Advanced Computational Methods in Heat Transfer IX 33 Estimating number of shells and determining the log mean temperature difference correction factor of shell and tube heat exchangers 3 4 S. K. Bhatti,
More informationThermal Unit Operation (ChEg3113)
Thermal Unit Operation (ChEg3113) Lecture 6- Double Pipe Heat Exchanger Design Instructor: Mr. Tedla Yeshitila (M.Sc.) Today Review Double pipe heat exchanger design procedure Example Review Deign of heat
More informationWelcome to the course in Heat Transfer (MMV031) L1. Martin Andersson & Zan Wu
Welcome to the course in Heat Transfer (MMV031) L1 Martin Andersson & Zan Wu Agenda Organisation Introduction to Heat Transfer Heat Exchangers (Ex 108) Course improvement compared to last years 2017: Amount
More informationThermal Analysis of Shell and Tube Heat Ex-Changer Using C and Ansys
Thermal Analysis of Shell and Tube Heat Ex-Changer Using C and Ansys A v.hari Haran,*, B g.ravindra Reddy and C b.sreehari a) PG Student Mechanical Engineering Department Siddharth Institute Of Engineering
More informationSimplified and approximated relations of heat transfer effectiveness for a steam condenser
Open Access Journal Journal of Power Technologies 92 (4) (2012) 258 265 journal homepage:papers.itc.pw.edu.pl Simplified and approximated relations of heat transfer effectiveness for a steam condenser
More informationHEAT TRANSFER AND EXCHANGERS
HEAT TRANSFER AND EXCHANGERS Although heat-transfer rates can be computed with reasonable accuracy for clean or new pipe, the effect of dirty or corroded pipe surfaces cannot he satisfactorily estimated.
More informationS.E. (Chemical) (Second Semester) EXAMINATION, 2011 HEAT TRANSFER (2008 PATTERN) Time : Three Hours Maximum Marks : 100
Total No. of Questions 12] [Total No. of Printed Pages 7 [4062]-186 S.E. (Chemical) (Second Semester) EXAMINATION, 2011 HEAT TRANSFER (2008 PATTERN) Time : Three Hours Maximum Marks : 100 N.B. : (i) Answers
More informationHeat and Mass Transfer Unit-1 Conduction
1. State Fourier s Law of conduction. Heat and Mass Transfer Unit-1 Conduction Part-A The rate of heat conduction is proportional to the area measured normal to the direction of heat flow and to the temperature
More informationS.E. (Chemical) (Second Semester) EXAMINATION, 2012 HEAT TRANSFER (2008 PATTERN) Time : Three Hours Maximum Marks : 100
Total No. of Questions 12] [Total No. of Printed Pages 7 Seat No. [4162]-187 S.E. (Chemical) (Second Semester) EXAMINATION, 2012 HEAT TRANSFER (2008 PATTERN) Time : Three Hours Maximum Marks : 100 N.B.
More informationCountercurrent heat exchanger
Countercurrent heat exchanger 1. Theoretical summary The basic operating principles and the simplified calculations regarding the counter current heat exchanger were discussed in the subject Chemical Unit
More informationPROPOSED SOLUTION - ASSIGNMENT 5
Norwegian University of Science and Technology Course: Process Integration Department of Energy and Process Engineering Number: TEP 5 Trondheim, 0..07, T. Gundersen Part: Heat Exchanger Networks PROPOSED
More informationThe average velocity of water in the tube and the Reynolds number are Hot R-134a
hater 0:, 8, 4, 47, 50, 5, 55, 7, 75, 77, 8 and 85. 0- Refrigerant-4a is cooled by water a double-ie heat exchanger. he overall heat transfer coefficient is to be determed. Assumtions he thermal resistance
More informationTrue/False. Circle the correct answer. (1pt each, 7pts total) 3. Radiation doesn t occur in materials that are transparent such as gases.
ME 323 Sample Final Exam. 120pts total True/False. Circle the correct answer. (1pt each, 7pts total) 1. A solid angle of 2π steradians defines a hemispherical shell. T F 2. The Earth irradiates the Sun.
More informationHeat Transfer Performance in Double-Pass Flat-Plate Heat Exchangers with External Recycle
Journal of Applied Science and Engineering, Vol. 17, No. 3, pp. 293 304 (2014) DOI: 10.6180/jase.2014.17.3.10 Heat Transfer Performance in Double-Pass Flat-Plate Heat Exchangers with External Recycle Ho-Ming
More informationEXPERIMENTAL AND THEORETICAL ANALYSIS OF TRIPLE CONCENTRIC TUBE HEAT EXCHANGER
EXPERIMENTAL AND THEORETICAL ANALYSIS OF TRIPLE CONCENTRIC TUBE HEAT EXCHANGER 1 Pravin M. Shinde, 2 Ganesh S. Yeole, 3 Abhijeet B. Mohite, 4 Bhagyashree H. Mahajan. 5 Prof. D. K. Sharma. 6 Prof. A. K.
More informationTOPIC 2 [A] STEADY STATE HEAT CONDUCTION
TOPIC 2 [A] STEADY STATE HEAT CONDUCTION CLASS TUTORIAL 1. The walls of a refrigerated truck consist of 1.2 mm thick steel sheet (k=18 W/m-K) at the outer surface, 22 mm thick cork (k=0.04 W/m-K) on the
More informationThermodynamics I Spring 1432/1433H (2011/2012H) Saturday, Wednesday 8:00am - 10:00am & Monday 8:00am - 9:00am MEP 261 Class ZA
Thermodynamics I Spring 1432/1433H (2011/2012H) Saturday, Wednesday 8:00am - 10:00am & Monday 8:00am - 9:00am MEP 261 Class ZA Dr. Walid A. Aissa Associate Professor, Mech. Engg. Dept. Faculty of Engineering
More information11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics
Effect of Axial Wall Conduction and Ambient Heat-in-Leak on the Performance of a Two- Fluid Counter-Flow Cryogenic Heat Exchanger, Using Finite Element Method Avinash Gouda D.*, Animesh Kumar Sinha, Chiranth
More informationOPTIMIZATION OF AN INDUSTRIAL HEAT EXCHANGER BY THE MINIMALIZATION OF ENTROPY SVOČ FST 2017
OPTIMIZATION OF AN INDUSTRIAL HEAT EXCHANGER BY THE MINIMALIZATION OF ENTROPY SVOČ FST 217 Bc. Richard Pisinger, University of West Bohemia, Univerzitní 8, 36 14 Pilsen Czech Republic ABSTRACT A second
More informationDesign and Temperature Analysis on Heat Exchanger with TEMA Standard Codes
Design and Temperature Analysis on Heat Exchanger with TEMA Standard Codes Adesh Dhope 1, Omkar Desai 2, Prof. V. Verma 3 1 Student, Department of Mechanical Engineering,Smt. KashibaiNavale college of
More informationEFFECT OF AMBIENT HEAT-IN-LEAK AND LONGITUDINAL WALL CONDUCTION ON A THREE-FLUID PARALLEL FLOW CRYOGENIC HEAT EXCHANGER
EFFECT OF AMBIENT HEAT-IN-LEAK AND LONGITUDINAL WALL CONDUCTION ON A THREE-FLUID PARALLEL FLOW CRYOGENIC HEAT EXCHANGER V.Krishna a, *, Spoorthi S. a, Pradeep G. Hegde b and K. N. Seetharamu a *Author
More informationHeat Transfer Co-efficient and Effectiveness for Water Using Spiral Coil Heat Exchanger: A Comprehensive Study
Global Science and Technology Journal Vol. 1. No. 1. July 2013 Issue. Pp.12-22 Heat Transfer Co-efficient and Effectiveness for Water Using Spiral Coil Heat Exchanger: A Comprehensive Study M A. Hossain
More informationChapter 7: External Forced Convection. Dr Ali Jawarneh Department of Mechanical Engineering Hashemite University
Chapter 7: External Forced Convection Dr Ali Jawarneh Department of Mechanical Engineering Hashemite University Objectives When you finish studying this chapter, you should be able to: Distinguish between
More informationTheory. Humidity h of an air-vapor mixture is defined as the mass ratio of water vapor and dry air,
Theory Background In a cooling tower with open water circulation, heat is removed from water because of the material and heat exchange between the water and the ambient air. The cooling tower is a special
More informationCHAPTER 3 SHELL AND TUBE HEAT EXCHANGER
20 CHAPTER 3 SHELL AND TUBE HEAT EXCHANGER 3.1 INTRODUCTION A Shell and Tube Heat Exchanger is usually used for higher pressure applications, which consists of a series of tubes, through which one of the
More informationAnalytical Study on Thermal and Mechanical Design of Printed Circuit Heat Exchanger
INL/EXT-13-30047 Analytical Study on Thermal and Mechanical Design of Printed Circuit Heat Exchanger Su-Jong Yoon Piyush Sabharwall Eung-Soo Kim September 2013 The INL is a U.S. Department of Energy National
More informationExperiment 1. Measurement of Thermal Conductivity of a Metal (Brass) Bar
Experiment 1 Measurement of Thermal Conductivity of a Metal (Brass) Bar Introduction: Thermal conductivity is a measure of the ability of a substance to conduct heat, determined by the rate of heat flow
More informationCHAPTER 5 MASS AND ENERGY ANALYSIS OF CONTROL VOLUMES
Thermodynamics: An Engineering Approach 8th Edition in SI Units Yunus A. Çengel, Michael A. Boles McGraw-Hill, 2015 CHAPTER 5 MASS AND ENERGY ANALYSIS OF CONTROL VOLUMES Lecture slides by Dr. Fawzi Elfghi
More informationThe Research of Heat Transfer Area for 55/19 Steam Generator
Journal of Power and Energy Engineering, 205, 3, 47-422 Published Online April 205 in SciRes. http://www.scirp.org/journal/jpee http://dx.doi.org/0.4236/jpee.205.34056 The Research of Heat Transfer Area
More informationCircle one: School of Mechanical Engineering Purdue University ME315 Heat and Mass Transfer. Exam #2. April 3, 2014
Circle one: Div. 1 (12:30 pm, Prof. Choi) Div. 2 (9:30 am, Prof. Xu) School of Mechanical Engineering Purdue University ME315 Heat and Mass Transfer Exam #2 April 3, 2014 Instructions: Write your name
More informationShell/Integral Balances (SIB)
Shell/Integral Balances (SIB) Shell/Integral Balances Shell or integral (macroscopic) balances are often relatively simple to solve, both conceptually and mechanically, as only limited data is necessary.
More informationThe black box model of a double tube counter flow heat exchanger
DOI 10.1007/s00231-014-1482-2 ORIGINAL The black box model of a double tube counter flow heat exchanger Rafał Laskowski Received: 18 January 2014 / Accepted: 18 December 2014 / Published online: December
More information10 minutes reading time is allowed for this paper.
EGT1 ENGINEERING TRIPOS PART IB Tuesday 31 May 2016 2 to 4 Paper 4 THERMOFLUID MECHANICS Answer not more than four questions. Answer not more than two questions from each section. All questions carry the
More informationChapter 3 NATURAL CONVECTION
Fundamentals of Thermal-Fluid Sciences, 3rd Edition Yunus A. Cengel, Robert H. Turner, John M. Cimbala McGraw-Hill, 2008 Chapter 3 NATURAL CONVECTION Mehmet Kanoglu Copyright The McGraw-Hill Companies,
More informationPrinciples of Food and Bioprocess Engineering (FS 231) Exam 2 Part A -- Closed Book (50 points)
Principles of Food and Bioprocess Engineering (FS 231) Exam 2 Part A -- Closed Book (50 points) 1. Are the following statements true or false? (20 points) a. Thermal conductivity of a substance is a measure
More informationChapter 5: The First Law of Thermodynamics: Closed Systems
Chapter 5: The First Law of Thermodynamics: Closed Systems The first law of thermodynamics can be simply stated as follows: during an interaction between a system and its surroundings, the amount of energy
More informationHeat exchangers: Heat exchanger types:
Heat exhangers: he proess of heat exhange between two fluids that are at different temperatures and separated by a solid wall ours in many engineering appliations. he devie used to implement this exhange
More informationComparative Analysis of Different Fluids in One Shell Pass And Two Tube Heat Exchanger
American Journal of Engineering Research (AJER) 2016 American Journal of Engineering Research (AJER) e-issn: 2320-0847 p-issn : 2320-0936 Volume-5, Issue-8, pp-81-87 wwwajerorg Research Paper Open Access
More informationEXPERIMENTAL AND NUMERICAL STUDIES OF A SPIRAL PLATE HEAT EXCHANGER
THERMAL SCIENCE: Year 2014, Vol. 18, No. 4, pp. 1355-1360 1355 EXPERIMENTAL AND NUMERICAL STUDIES OF A SPIRAL PLATE HEAT EXCHANGER by Rangasamy RAJAVEL Department of Mechanical Engineering, AMET University,
More informationHEAT TRANSFER 1 INTRODUCTION AND BASIC CONCEPTS 5 2 CONDUCTION
HEAT TRANSFER 1 INTRODUCTION AND BASIC CONCEPTS 5 2 CONDUCTION 11 Fourier s Law of Heat Conduction, General Conduction Equation Based on Cartesian Coordinates, Heat Transfer Through a Wall, Composite Wall
More informationPROBLEM 8.3 ( ) p = kg m 1m s m 1000 m = kg s m = bar < P = N m 0.25 m 4 1m s = 1418 N m s = 1.
PROBLEM 8.3 KNOWN: Temperature and velocity of water flow in a pipe of prescribed dimensions. FIND: Pressure drop and pump power requirement for (a) a smooth pipe, (b) a cast iron pipe with a clean surface,
More informationSpecific heat capacity. Convective heat transfer coefficient. Thermal diffusivity. Lc ft, m Characteristic length (r for cylinder or sphere; for slab)
Important Heat Transfer Parameters CBE 150A Midterm #3 Review Sheet General Parameters: q or or Heat transfer rate Heat flux (per unit area) Cp Specific heat capacity k Thermal conductivity h Convective
More informationFatima
Fatima QUESTION BANK DEPARTMENT: MECH SEMESTER: IV SUBJECT CODE / Name: ME 2251/HEAT AND MASS TRANSFER UNIT I: CONDUCTION PART -A (2 Marks) 1. What is Fourier's Law of heat conduction? (May 05, May 06,
More informationfirst law of ThermodyNamics
first law of ThermodyNamics First law of thermodynamics - Principle of conservation of energy - Energy can be neither created nor destroyed Basic statement When any closed system is taken through a cycle,
More informationarxiv: v1 [physics.app-ph] 25 Mar 2018
Improvement of heat exchanger efficiency by using hydraulic and thermal entrance regions arxiv:1803.09255v1 [physics.app-ph] 25 Mar 2018 Abstract Alexey Andrianov a, Alexander Ustinov a, Dmitry Loginov
More informationAttempt ALL QUESTIONS IN SECTION A and ANY TWO QUESTIONS IN SECTION B Graph paper will be provided.
UNIVERSITY OF EAST ANGLIA School of Mathematics Main Series UG Examination 2017-2018 ENGINEERING PRINCIPLES AND LAWS ENG-4002Y Time allowed: 3 Hours Attempt ALL QUESTIONS IN SECTION A and ANY TWO QUESTIONS
More informationChapter 3: Steady Heat Conduction. Dr Ali Jawarneh Department of Mechanical Engineering Hashemite University
Chapter 3: Steady Heat Conduction Dr Ali Jawarneh Department of Mechanical Engineering Hashemite University Objectives When you finish studying this chapter, you should be able to: Understand the concept
More informationAxial profiles of heat transfer coefficients in a liquid film evaporator
Axial profiles of heat transfer coefficients in a liquid film evaporator Pavel Timár, Ján Stopka, Vladimír Báleš Department of Chemical and Biochemical Engineering, Faculty of Chemical and Food Technology,
More informationSHELL-AND-TUBE TEST PROBLEMS
SHELL-AND-TUBE TEST PROBLEMS The problems that have been used to validate some of the capabilities in INSTED for the analysis of shell-and-tube heat exchanger are discussed in this chapter. You should
More informationLectures on Applied Reactor Technology and Nuclear Power Safety. Lecture No 6
Lectures on Nuclear Power Safety Lecture No 6 Title: Introduction to Thermal-Hydraulic Analysis of Nuclear Reactor Cores Department of Energy Technology KTH Spring 2005 Slide No 1 Outline of the Lecture
More information