DEFINITION OF HEAT TRANSFER | Heat transfer is energy in transit due to temperature difference . Whenever there exists a temperature difference in a medium or between media‚ heat transfer must occur. The basic requirement for heat transfer is the presence of temperature difference . There can be no net heat transfer between two mediums that are at the same temperature. The temperature difference is the driving force for heat transfer‚ just as the voltage difference is the driving force for electric
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FREESTUDY HEAT TRANSFER TUTORIAL 2 CONVECTION AND RADIATION This is the second tutorial in the series on basic heat transfer theory plus some elements of advanced theory. The tutorials are designed to bring the student to a level where he or she can solve problems ranging from basic level to dealing with practical heat exchangers. On completion of this tutorial the student should be able to do the following. • • Explain the use of the surface heat transfer coefficient. • Explain
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FUNDAMENTAL CONCEPTS Heat transfer is energy in transit‚ which occurs as a result of temperature gradient or difference. This temperature difference is thought of as a driving force that causes heat to flow. The concepts of heat transfer and temperature‚ the key words in the discipline of heat transfer‚ are 2 of the most basic concepts of thermodynamics. dffffffffff rifffff orfff ffffffffff fv ing ff ce Rate of transport process= fffffffffff or rate = coefficient B driving force resist
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Heat Transfer Through Jacket Objective The objective of this example is to analyze heat transfer in a pilot plant using simulation models. The first step is to use pilot plant data to calculate heat transfer parameters. The second part involves using simulation models to examine the trade-off between jacket parameters and heating times. Process Description Assumptions: The stirred tank is assumed to be perfectly mixed. The contributions of agitator work‚ heat loss to environment
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overall heat transfer coefficient on the outer surface of the covered pipe is 10 W/m2.K. if the velocity of the steam is 10 m/s‚ at what point along the pipe will the steam begin condensing and what distance will be required for the steam to reach a mean temperature of 100 oC? Question 2: Consider a horizontal‚ thin walled circular tube of diameter D = 0.025 m submerge in a container of n-octadecane (paraffin)‚ which is used to store thermal energy. As hot water flows through the tube‚ heat is
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resistance R0 = 100 Ω at 0o C. If the resistance RT = 197.7 Ω in an oil bath‚ what is the temperature of the oil in the bath‚ given that RT = R0(1+αT)? Take R0 = 100 Ω R0 = resistance at 0o C α = 3.9083 x 10-3 /o C (2 marks) NDE Thermodynamics and Heat Transfer Exam 2008 Name: _______________________________________ Read all the instructions before starting Do not open this paper until instructed Time allowed: 2 hours (plus 5 minutes reading time) Attempt ALL question in Section A (questions 1 – 12)
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HEAT TRANSFER MECHANISMS Heat energy is being transferred from one location to another because of a temperature difference. The three mechanisms for heat transfer are: • Conduction. When you grip the hot handle of a pan on a stove‚ you feel conduction in action. Heat flows from the pan and along the length of the handle to its cooler free end. This is because one end of the rod is held at the high temperature‚ and the other end stays at the lower temperature. Although the rod itself doesn’t
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Fi l +m = Fil + Fim Ji Gij qij i‚ Ji‚ Ai qij=(JiJj)/(1/AiFij) blackbody Ji=Ei(T) function of temperature Radiation network to find flux or potential 40 to 50 % ison radiation Heat exchanger U fouling factor will increase the resistance of heat transfer. how to include into the overall equation (mcp)h Th‚ in Tc‚ out (mcp)c Tc‚in You want to know the cooling effect energy conservation Q= {mcp(Th‚iTh‚o)}h ={mcp(Tc‚oTc‚i) }c Delta Tlm log mean
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situation for thick pipes is‚ however‚ more complex. [pic] The figure shown above represents the condition in a thick walled pipe. The area for heat flow is proportional to the radius – as may be seen‚ the area at the outside wall of the pipe is much greater than the middle. As a result the temperature gradient is inversely proportional to the radius. The heat flow ‘per unit length of pipe’ at any radius r‚ is [pic] cf. [pic] Note: Area‚[pic] Note there is no length of pipe (l) in this equation
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State Heat Transfer laboratory were to study the rates of heat transfer for different materials of varying sizes‚ to develop an understanding of the concepts of forced and free convection and to determine the heat transfer coefficients for several rods. These objectives were met by heating several rods and allowing them to cool through free convection in air‚ free convection in water and forced convection in water- while monitoring their change in temperature over change in time. Seven heat transfer
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