Fundamentals of Heat and Mass Transfer 7th Edition solutions

Fundamentals of Heat and Mass Transfer 7
In a fire-tube boiler, hot products of combustion flow-ing through an array of thin-walled tubes are used toboil water flowing over the tubes. At the time of instal-lation, the overall heat transfer coefficient was400 W/m2?K. After 1 year of use, the inner and outertube surfaces are fouled, with corr

Fundamentals of Heat and Mass Transfer 7
A type-302 stainless steel tube of inner and outer diam-eters Di?22 mm and Do?27 mm, respectively, isused in a cross-flow heat exchanger. The fouling fac-tors, R?, for the inner and outer surfaces are estimatedto be 0.0004 and 0.0002 m2?K/W, respectively. a) Determine the overall heat transfer coeffi

Fundamentals of Heat and Mass Transfer 7
A shell-and-tube heat exchanger is to heat an acidic liquidthat flows in unfinned tubes of inside and outside diame-ters Di?10 mm and Do?11 mm, respectively. A hotgas flows on the shell side. To avoid corrosion of the tubematerial, the engineer may specify either a Ni-Cr-Mo corrosion-resistant metal

Fundamentals of Heat and Mass Transfer 7
A steel tube (k?50 W/m?K) of inner and outer diame-ters Di?20 mm and Do?26 mm, respectively, is usedto transfer heat from hot gases flowing over the tube(hh?200 W/m2?K) to cold water flowing through thetube (hc?8000 W/m2?K). What is the cold-side overallheat transfer coefficient Uc? To enhance heat t

Fundamentals of Heat and Mass Transfer 7
A heat recovery device involves transferring energyfrom the hot flue gases passing through an annularregion to pressurized water flowing through the innertube of the annulus. The inner tube has inner and outer diameters of 24 and 30 mm and is connected by eightstruts to an insulated outer tube of 60-

Fundamentals of Heat and Mass Transfer 7
A novel design for a condenser consists of a tube ofthermal conductivity 200 W/m?K with longitudinal finssnugly fitted into a larger tube. Condensing refrigerantat 45?C flows axially through the inner tube, while waterat a flow rate of 0.012 kg/s passes through the six chan-nels around the inner tube

Fundamentals of Heat and Mass Transfer 7
The condenser of a steam power plant containsN?1000 brass tubes (kt?110 W/m?K), each ofinner and outer diameters, Di?25 mm and Do? 28 mm, respectively. Steam condensation on the outersurfaces of the tubes is characterized by a convectioncoefficient of ho?10,000 W/m2?K.(a) If cooling water from a larg

Fundamentals of Heat and Mass Transfer 7
Thin-walled aluminum tubes of diameter D?10 mmare used in the condenser of an air conditioner. Undernormal operating conditions, a convection coefficientof hi?5000 W/m2?K is associated with condensationon the inner surface of the tubes, while a coefficient ofho?100 W/m2?K is maintained by airflow ove

Fundamentals of Heat and Mass Transfer 7
A finned-tube, cross-flow heat exchanger is to use theexhaust of a gas turbine to heat pressurized water. Labo-ratory measurements are performed on a prototype ver-sion of the exchanger, which has a surface area of 10 m2,to determine the overall heat transfer coefficient as afunction of operating con

Fundamentals of Heat and Mass Transfer 7
Water at a rate of 45,500 kg/h is heated from 80 to150C in a heat exchanger having two shell passes and eight tube passes with a total surface area of 925 m2.Hot exhaust gases having approximately the same thermophysical properties as air enter at 350C and exit at 175C. Determine the overall heat tra

Fundamentals of Heat and Mass Transfer 7
A novel heat exchanger concept consists of a largenumber of extruded polypropylene sheets (k?0.17W/m?K), each having a fin-like geometry, that aresubsequently stacked and melted together to form theheat exchanger core. Besides being inexpensive, the heatexchanger can be easily recycled at the end of

Fundamentals of Heat and Mass Transfer 7
The properties and flow rates for the hot and cold flu-ids of a heat exchanger are shown in the followingtable. Which fluid limits the heat transfer rate of theexchanger? Explain your choice.Hot flui Cold fluiDensity, kg/m3997 1247Specific heat, 4179 2564Thermal conductivity, 0.

Fundamentals of Heat and Mass Transfer 7
A process fluid having a specific heat of 3500 J/kg?Kand flowing at 2 kg/s is to be cooled from 80?C to50?C with chilled water, which is supplied at a temper-ature of 15?C and a flow rate of 2.5 kg/s. Assuming anoverall heat transfer coefficient of 2000 W/m2?K, cal-culate the required heat transfer a

Fundamentals of Heat and Mass Transfer 7
A shell-and-tube exchanger (two shells, four tube passes)is used to heat 10,000 kg/h of pressurized water from35 to 120C with 5000 kg/h pressurized water enteringthe exchanger at 300C. If the overall heat transfercoefficient is 1500 W/m2?K, determine the requiredheat exchanger area.

Fundamentals of Heat and Mass Transfer 7
Consider the heat exchanger of Problem 11.14. Afterseveral years of operation, it is observed that the outlettemperature of the cold water reaches only 95C ratherthan the desired 120C for the same flow rates andinlet temperatures of the fluids. Determine the cumula-tive (inner and outer surface) foul

Fundamentals of Heat and Mass Transfer 7
The hot and cold inlet temperatures to a concentrictube heat exchanger are Th,i?200?C, Tc,i?100?C,respectively. The outlet temperatures are Th,o?110?Cand Tc,o?125?C. Is the heat exchanger operating in aparallel flow or in a counterflow configuration? Whatis the heat exchanger effectiveness? What is t

Fundamentals of Heat and Mass Transfer 7
A concentric tube heat exchanger of length L?2m isused to thermally process a pharmaceutical productflowing at a mean velocity of um,c?0.1 m/s with aninlet temperature of Tc,i?20?C. The inner tube ofdiameter Di?10 mm is thin walled, and the exteriorof the outer tube (Do?20 mm) is well insulated.Water

Fundamentals of Heat and Mass Transfer 7
A counterflow, concentric tube heat exchanger isdesigned to heat water from 20 to 80?C using hot oil,which is supplied to the annulus at 160?C and dis-charged at 140?C. The thin-walled inner tube has adiameter of Di?20 mm, and the overall heat transfer coefficient is 500 W/m2?K. The design condition

Fundamentals of Heat and Mass Transfer 7
Consider the counterflow, concentric tube heatexchanger of Example 11.1. The designer wishes toconsider the effect of the cooling water flow rate onthe tube length. All other conditions, including theoutlet oil temperature of 60?C, remain the same.(a) From the analysis of Example 11.1, we saw thatthe

Fundamentals of Heat and Mass Transfer 7
Consider a concentric tube heat exchanger with an areaof 50 m2operating under the following conditions:Hot flui Cold fluiHeat capacity rate, kW/K 63Inlet temperature, 60 30Outlet temperature, 54(a) Determine the outlet temperature of the hot fluid.(b) Is the heat exchanger op

Fundamentals of Heat and Mass Transfer 7
As part of a senior project, a student was given theassignment to design a heat exchanger that meets the following specifications:Hot water28 90 Like many real-world situations, the customer hasntrevealed, or doesnt know, additional requirements thatwould allow you to proceed directly to a f

Fundamentals of Heat and Mass Transfer 7
A shell-and-tube heat exchanger must be designed toheat 2.5 kg/s of water from 15 to 85?C. The heating isto be accomplished by passing hot engine oil, which is available at 160?C, through the shell side of theexchanger. The oil is known to provide an averageconvection coefficient of ho?400 W/m2?K on

Fundamentals of Heat and Mass Transfer 7
A concentric tube heat exchanger for cooling lubri-cating oil is comprised of a thin-walled inner tube of25-mm diameter carrying water and an outer tube of45-mm diameter carrying the oil. The exchangeroperates in counterflow with an overall heat transfercoefficient of 60 W/m2?K and the tabulated aver

Fundamentals of Heat and Mass Transfer 7
A counterflow, concentric tube heat exchanger usedfor engine cooling has been in service for an extendedperiod of time. The heat transfer surface area of theexchanger is 5 m2, and the design valueof the overallconvection coefficient is 38 W/m2?K. During a testrun, engine oil flowing at 0.1 kg/s is co

Fundamentals of Heat and Mass Transfer 7
An automobile radiator may be viewed as a cross-flowheat exchanger with both fluids unmixed. Water,which has a flow rate of 0.05 kg/s, enters the radiatorat 400 K and is to leave at 330 K. The water is cooledby air that enters at 0.75 kg/s and 300 K.(a) If the overall heat transfer coefficient is 200

Fundamentals of Heat and Mass Transfer 7
Hot air for a large-scale drying operation is to be pro-duced by routing the air over a tube bank (unmixed),while products of combustion are routed through the tubes. The surface area of the cross- flow heatexchanger is A?25 m2, and for the proposed operat-ing conditions, the manufacturer specifies a

Fundamentals of Heat and Mass Transfer 7
In a dairy operation, milk at a flow rate of 250 L /h anda cow-bodytemperature of 38.6?C must be chilled to asafe-to-store temperature of 13?C or less. Groundwater at 10?C is available at a flow rate of 0.72 m3/h.The density and specific heat of milk are 1030 kg/m3and 3860 J/kg?K, respectively.(a) De

Fundamentals of Heat and Mass Transfer 7
A shell-and-tube heat exchanger with one shell passand two tube passes is used as a regenerator,to pre-heat milk before it is pasteurized. Cold milk enters theregenerator at Tc,i?5?C, while hot milk, which hascompleted the pasteurization process, enters at Th,i?70?C. After leaving the regenerator, th

Fundamentals of Heat and Mass Transfer 7
A twin-tube, counterflow heat exchanger operates withbalanced flow rates of 0.003 kg/s for the hot and coldairstreams. The cold stream enters at 280 K and mustbe heated to 340 K using hot air at 360 K. The averagepressure of the airstreams is 1 atm and the maximumallowable pressure drop for the cold

Fundamentals of Heat and Mass Transfer 7
A 5-m-long, twin-tube, counterflow heat exchanger,such as that illustrated in Problem 11.29, is used to heatair for a drying operation. Each tube is made from plaincarbon steel (k?60 W/m?K) and has an inner diameterand wall thickness of 50 mm and 4 mm, respectively.The thermal resistance per unit len

Fundamentals of Heat and Mass Transfer 7
Hot water for an industrial washing operation is pro-duced by recovering heat from the flue gases of a fur-nace. A cross-flow heat exchanger is used, with thegases passing over the tubes and the water making asingle pass through the tubes. The steel tubes(k?60 W/m?K) have inner and outer diameters of

Fundamentals of Heat and Mass Transfer 7
A single-pass, cross-flow heat exchanger uses hotexhaust gases (mixed) to heat water (unmixed) from30 to 80?C at a rate of 3 kg/s. The exhaust gases, hav-ing thermophysical properties similar to air, enter andexit the exchanger at 225 and 100?C, respectively. Ifthe overall heat transfer coefficient i

Fundamentals of Heat and Mass Transfer 7
Consider the fluid conditions and overall heat transfercoefficient of Problem 11.32 for a concentric tube heatexchanger operating in parallel flow. The thin-walledseparator tube has a diameter of 100 mm.(a) Determine the required length for the exchanger.(b) Assuming water flow inside the separator t

Fundamentals of Heat and Mass Transfer 7
The compartment heater of an automobile exchangesheat between warm radiator fluid and cooler outsideair. The flow rate of water is large compared to the air,and the effectiveness, ?, of the heater is known todepend on the flow rate of air according to the rela-tion, ? .(a) If the fan is switched to h

Fundamentals of Heat and Mass Transfer 7
A counterflow, twin-tube heat exchanger is made bybrazing two circular nickel tubes, each 40 m long,together as shown below. Hot water flows through thesmaller tube of 10-mm diameter and air at atmos-pheric pressure flows through the larger tube of 30-mm diameter. Both tubes have a wall thickness of2

Fundamentals of Heat and Mass Transfer 7
Consider a coupledshell-in-tube heat exchange deviceconsisting of two identical heat exchangers A and B. Air flows on the shell side of heat exchanger A, enter-ing at Th,i,A?520 K and . Ammoniaflows in the shell of heat exchanger B, entering atTc,i,B?280 K, . The tube-side flow iscommon to both heat

Fundamentals of Heat and Mass Transfer 7
Consider Problem 11.36.(a) For , determine the outlet airand ammonia temperatures, as well as the heattransfer rate.(b) Plot the outlet air and outlet ammonia tempera-tures versus the water flow rate over the range 5 kg/s.

Fundamentals of Heat and Mass Transfer 7
For health reasons, public spaces require the continu-ous exchange of a specified mass of stale indoor airwith fresh outdoor air. To conserve energy during theheating season, it is expedient to recover the thermalenergy in the exhausted, warm indoor air and transferit to the incoming, cold fresh air.

Fundamentals of Heat and Mass Transfer 7
A cross-flow heat exchanger used in a cardiopulmonarybypass procedure cools blood flowing at 5 L/min from a body temperature of 37?C to 25?C in order to inducebody hypothermia, which reduces metabolic andoxygen requirements. The coolant is ice water at 0?C,and its flow rate is adjusted to provide an

Fundamentals of Heat and Mass Transfer 7
Saturated steam at 0.14 bar is condensed in a shell-and-tube heat exchanger with one shell pass and two tubepasses consisting of 130 brass tubes, each with a lengthper pass of 2 m. The tubes have inner and outer diame-ters of 13.4 and 15.9 mm, respectively. Cooling waterenters the tubes at 20?C with

Fundamentals of Heat and Mass Transfer 7
A feedwater heater that supplies a boiler consists of ashell-and-tube heat exchanger with one shell pass andtwo tube passes. One hundred thin-walled tubes eachhave a diameter of 20 mm and a length (per pass) of2 m. Under normal operating conditions water entersthe tubes at 10 kg/s and 290 K and is he

Fundamentals of Heat and Mass Transfer 7
Saturated steam at 110?C is condensed in a shell-and-tube heat exchanger (1 shell pass; 2, 4,...tubepasses) with a UAvalue of 2.5 kW/K. Cooling waterenters at 40?C.(a) Calculate the cooling water flow rate required tomaintain a heat rate of 150 kW.(b) Assuming that UAis independent of flow rate, cal-

Fundamentals of Heat and Mass Transfer 7
A shell-and-tube heat exchanger (1 shell pass, 2 tubepasses) is to be used to condense 2.73 kg/s of saturatedsteam at 340 K. Condensation occurs on the outer tubesurfaces, and the corresponding convection coefficientis 10,000 W/m2?K. The temperature of the coolingwater entering the tubes is 15?C, and

Fundamentals of Heat and Mass Transfer 7
Saturated water vapor leaves a steam turbine at a flowrate of 1.5 kg/s and a pressure of 0.51 bar. The vapor isto be completely condensed to saturated liquid in ashell-and-tube heat exchanger that uses city water asthe cold fluid. The water enters the thin-walled tubesat 17?C and is to leave at 57?C.

Fundamentals of Heat and Mass Transfer 7
A two-fluid heat exchanger has inlet and outlet tem-peratures of 65 and 40?C for the hot fluid and 15 and30?C for the cold fluid. Can you tell whether thisexchanger is operating under counterflow or parallel-flow conditions? Determine the effectiveness of theheat exchanger.

Fundamentals of Heat and Mass Transfer 7
The human brain is especially sensitive to elevatedtemperatures. The cool blood in the veins leaving theface and neck and returning to the heart may contributeto thermal regulation of the brain by cooling the arte-rial blood flowing to the brain. Consider a vein andartery running between the chest an

Fundamentals of Heat and Mass Transfer 7
Consider a very long,concentric tube heat exchangerhaving hot and cold water inlet temperatures of 85 and15?C. The flow rate of the hot water is twice that of the cold water. Assuming equivalent hot and cold waterspecific heats, determine the hot water outlet tempera-ture for the following modes of o

Fundamentals of Heat and Mass Transfer 7
A plate-fin heat exchanger is used to condense a satu-rated refrigerant vapor in an air-conditioning system.The vapor has a saturation temperature of 45?C, and acondensation rate of 0.015 kg/s is dictated by systemperformance requirements. The frontal area of thecondenser is fixed at Afr?0.25 m2by in

Fundamentals of Heat and Mass Transfer 7
A shell-and-tube heat exchanger is to heat 10,000 kg/hof water from 16 to 84?C by hot engine oil flowingthrough the shell. The oil makes a single shell pass,entering at 160?C and leaving at 94?C, with an averageheat transfer coefficient of 400 W/m2?K. The waterflows through 11 brass tubes of 22.9-mm

Fundamentals of Heat and Mass Transfer 7
In a supercomputer, signal propagation delays arereduced by resorting to high-density circuit arrange-ments which are cooled by immersing them in a specialdielectric liquid. The fluid is pumped in a closed loopthrough the computer and an adjoining shell-and-tubeheat exchanger having one shell and two

Fundamentals of Heat and Mass Transfer 7
Untapped geothermal sites in the United States havethe estimated potential to deliver 100,000 MW (elec-tric) of new, clean energy. The key component in ageothermal power plant is a heat exchanger that trans-fers thermal energy from hot, geothermal brine to asecond fluid that is evaporated in the heat

Fundamentals of Heat and Mass Transfer 7
An energy storage system is proposed to absorb ther-mal energy collected during the day with a solar col-lector and release thermal energy at night to heat abuilding. The key component of the system is a shell-and-tube heat exchanger with the shell side filled withn-octadecane (see Problem 8.47).(a)

Fundamentals of Heat and Mass Transfer 7
A shell-and-tube heat exchanger consists of 135 thin-walled tubes in a double-pass arrangement, each of12.5-mm diameter with a total surface area of 47.5 m2.Water (the tube-side fluid) enters the heat exchanger at15?C and 6.5 kg/s and is heated by exhaust gas enteringat 200?C and 5 kg/s. The gas may

Fundamentals of Heat and Mass Transfer 7
An ocean thermal energy conversion system is beingproposed for electric power generation. Such a systemis based on the standard power cycle for which theworking fluid is evaporated, passed through a turbine,and subsequently condensed. The system is to be usedin very special locations for which the oc

Fundamentals of Heat and Mass Transfer 7
A single-pass, cross-flow heat exchanger with both flu-ids unmixed is being used to heat water (m.c?2 kg /s,cp?4200 J/kg?K) from 20?C to 100?C with hotexhaust gases (cp?1200 J/kg?K) entering at 320?C.What mass flow rate of exhaust gases is required?Assume that UAis equal to its design value of4700 W/

Fundamentals of Heat and Mass Transfer 7
Saturated process steam at 1 atm is condensed in ashell-and-tube heat exchanger (one shell, two tubepasses). Cooling water enters the tubes at 15?C with anaverage velocity of 3.5 m/s. The tubes are thin walledand made of copper with a diameter of 14 mm andlength of 0.5 m. The convective heat transfer

Fundamentals of Heat and Mass Transfer 7
The chief engineer at a university that is constructing alarge number of new student dormitories decides toinstall a counterflow concentric tube heat exchangeron each of the dormitory shower drains. The thin-walled copper drains are of diameter Di?50 mm.Wastewater from the shower enters the heat exch

Fundamentals of Heat and Mass Transfer 7
A shell-and-tube heat exchanger with one shell passand 20 tube passes uses hot water on the tube side toheat oil on the shell side. The single copper tube hasinner and outer diameters of 20 and 24 mm and alength per pass of 3 m. The water enters at 87?C and0.2 kg/s and leaves at 27?C. Inlet and outle

Fundamentals of Heat and Mass Transfer 7
The oil in an engine is cooled by air in a cross-flowheat exchanger where both fluids are unmixed. Atmos-pheric air enters at 30?C and 0.53 kg/s. Oil at0.026 kg/s enters at 75?C and flows through a tube of10-mm diameter. Assuming fully developed flow andconstant wall heat flux, estimate the oil-side

Fundamentals of Heat and Mass Transfer 7
A recuperator is a heat exchanger that heats the airused in a combustion process by extracting energyfrom the products of combustion (the flue gas). Con-sider using a single-pass, cross-flow heat exchanger asa recuperator.Eighty (80) silicon carbide ceramic tubes (k?20W/m?K) of inner and outer diamet

Fundamentals of Heat and Mass Transfer 7
Consider operation of the furnacerecuperator combi-nation of Problem 11.60 under conditions for whichchemical energy is converted to thermal energy in thecombustor at a rate of qcomb?2.0106W and energyis transferred from the combustion gases to the load inthe furnace at a rate of qload?1.4106W. Assum

Fundamentals of Heat and Mass Transfer 7
It is proposed that the exhaust gas from a naturalgaspowered electric generation plant be used togenerate steam in a shell-and-tube heat exchangerwith one shell and one tube pass. The steel tubeshave a thermal conductivity of 40 W/m?K, an innerdiameter of 50 mm, and a wall thickness of 4 mm.The exhau

Fundamentals of Heat and Mass Transfer 7
A recuperator is a heat exchanger that heats air used ina combustion process by extracting energy from theproducts of combustion. It can be used to increase the efficiency of a gas turbine by increasing the tem-perature of air entering the combustor.Consider a system for which the recuperator is a cr

Fundamentals of Heat and Mass Transfer 7
A concentric tube heat exchanger uses water, which isavailable at 15?C, to cool ethylene glycol from 100 to60?C. The water and glycol flow rates are each 0.5 kg/s.What are the maximum possible heat transfer rate andeffectiveness of the exchanger? Which is preferred, aparallel-flow or counterflow mode

Fundamentals of Heat and Mass Transfer 7
Water is used for both fluids (unmixed) flowingthrough a single-pass, cross-flow heat exchanger. Thehot water enters at 90?C and 10,000 kg/h, while thecold water enters at 10?C and 20,000 kg/h. If the effec-tiveness of the exchanger is 60%, determine the coldwater exit temperature.

Fundamentals of Heat and Mass Transfer 7
A cross-flow heat exchanger consists of a bundle of 32 tubes in a 0.6-m2duct. Hot water at 150?C and amean velocity of 0.5 m/s enters the tubes having inner and outer diameters of 10.2 and 12.5 mm. Atmosphericair at 10?C enters the exchanger with a volumetric flowrate of 1.0 m3/s. The convection heat

Fundamentals of Heat and Mass Transfer 7
Exhaust gas from a furnace is used to preheat the com-bustion air supplied to the furnace burners. The gas,which has a flow rate of 15 kg/s and an inlet temperatureof 1100 K, passes through a bundle of tubes, while theair, which has a flow rate of 10 kg/s and an inlet tem-perature of 300 K, is in cro

Fundamentals of Heat and Mass Transfer 7
Derive Equation 11.35a. Hint: See Section 8.3.3.

Fundamentals of Heat and Mass Transfer 7
A liquefied natural gas (LNG) regasification facilityutilizes a vertical heat exchanger or vaporizer that con-sists of a shell with a single-pass tube bundle used toconvert the fuel to its vapor form for subsequent deliv-ery through a land-based pipeline. Pressurized LNG isoff-loaded from an oceangoi

Fundamentals of Heat and Mass Transfer 7
Work Problem 11.69 for the situation where the sea-water is introduced to the top of the vaporizer, result-ing in counterflowing natural gas and seawater.

Fundamentals of Heat and Mass Transfer 7
Cooling of outdoor electronic equipment such as intelecommunications towers is difficult due to seasonaland diurnal variations of the air temperature, and poten-tial fouling of heat exchange surfaces due to dust accu-mulation or insect nesting. A concept to provide a nearlyconstant sink temperature i

Fundamentals of Heat and Mass Transfer 7
A shell-and-tube heat exchanger consisting of oneshell pass and two tube passes is used to transfer heatfrom an ethylene glycolwater solution (shell side) supplied from a rooftop solar collector to pure water(tube side) used for household purposes. The tubes areof inner and outer diameters Di?3.6 mm

Fundamentals of Heat and Mass Transfer 7
In analyzing thermodynamic cycles involving heatexchangers, it is useful to express the heat rate interms of an overall thermal resistance Rtand the inlettemperatures of the hot and cold fluids,The heat transfer rate can also be expressed in terms ofthe rate equations,(a) Derive a relation for Rlm/Rt

Fundamentals of Heat and Mass Transfer 7
The power needed to overcome wind and friction dragassociated with an automobile traveling at a constantvelocity of 25 m/s is 9 kW.(a) Determine the required heat transfer area of theradiator if the vehicle is equipped with an internalcombustion engine operating at an efficiency of21%. (Assume 79% of

Fundamentals of Heat and Mass Transfer 7
An air conditioner operating between indoor and out-door temperatures of 23 and 43?C, respectively,removes 5 kW from a building. The air conditionercan be modeled as a reversed Carnot heat engine withrefrigerant as the working fluid. The efficiency of themotor for the compressor and fan is 80%, and 0

Fundamentals of Heat and Mass Transfer 7
In a Rankine power system, 1.5 kg/s of steam leaves theturbine as saturated vapor at 0.51 bar. The steam is con-densed to saturated liquid by passing it over the tubes ofa shell-and-tube heat exchanger, while liquid water,having an inlet temperature of Tc,i?280 K, is passedthrough the tubes. The cond

Fundamentals of Heat and Mass Transfer 7
Consider a Rankine cycle with saturated steam leavingthe boiler at a pressure of 2 MPa and a condenser pres-sure of 10 kPa.(a) Calculate the thermal efficiency of the ideal Rankinecycle for these operating conditions.(b) If the net reversible work for the cycle is 0.5 MW,calculate the required flow r

Fundamentals of Heat and Mass Transfer 7
Consider the Rankine cycle of Problem 11.77, whichrejects 2.3 MW to the condenser, which is suppliedwith a cooling water flow rate of 70 kg/s at 15?C.(a) Calculate UA, a parameter that is indicative of thesize of the condenser required for this operatingcondition.(b) Consider now the situation where

Fundamentals of Heat and Mass Transfer 7
Consider a concentric tube heat exchanger character-ized by a uniform overall heat transfer coefficient andoperating under the following conditions:cpTiTo(kg/s)(J/kg?K) (C) (C)Cold fluid 0.125 4200 40 95Hot fluid 0.125 2100 210 What is the maximum possibl

Fundamentals of Heat and Mass Transfer 7
The floor space of any facility that houses shell-and-tube heat exchangers must be sufficiently large so the tube bundle can be serviced easily. A rule of thumbis that the floor space must be at least 2.5 times thelength of the tube bundle so that the bundle can be com-pletely removed from the shell

Fundamentals of Heat and Mass Transfer 7
Consider the influence of a finite sheet thickness inExample 11.2, when there are 40 gaps.(a) Determine the exterior dimension, L, of the heatexchanger core for a sheet thickness of t?0.8 mmfor pure aluminum (kal?237 W/m?K) and poly-vinylidene fluoride (PVDF, kpv?0.17 W/m?K)sheets. Neglect the thickn

Fundamentals of Heat and Mass Transfer 7
Hot exhaust gases are used in a shell-and-tubeexchanger to heat 2.5 kg/s of water from 35 to 85?C.The gases, assumed to have the properties of air, enter at 200?C and leave at 93?C. The overallheat transfer coefficient is 180 W/m2?K. Using the effectivenessNTU method, calculate the area of theheat ex

Fundamentals of Heat and Mass Transfer 7
In open heart surgery under hypothermic conditions,the patients blood is cooled before the surgery and rewarmed afterward. It is proposed that a concentrictube, counterflow heat exchanger of length 0.5 m beused for this purpose, with the thin-walled inner tubehaving a diameter of 55 mm. The specific

Fundamentals of Heat and Mass Transfer 7
Ethylene glycol and water, at 60 and 10?C, respec-tively, enter a shell-and-tube heat exchanger for whichthe total heat transfer area is 15 m2. With ethylene gly-col and water flow rates of 2 and 5 kg/s, respectively,the overall heat transfer coefficient is 800 W/m2?K.(a) Determine the rate of heat t

Fundamentals of Heat and Mass Transfer 7
A boiler used to generate saturated steam is in the formof an unfinned, cross-flow heat exchanger, with waterflowing through the tubes and a high-temperature gas incross flow over the tubes. The gas, which has a specificheat of 1120 J/kg?K and a mass flow rate of 10 kg/s,enters the heat exchanger at

Fundamentals of Heat and Mass Transfer 7
Waste heat from the exhaust gas of an industrial fur-nace is recovered by mounting a bank of unfinnedtubes in the furnace stack. Pressurized water at a flowrate of 0.025 kg/s makes a single pass through eachofthe tubes, while the exhaust gas, which has anupstream velocity of 5.0 m/s, moves in cross f

Fundamentals of Heat and Mass Transfer 7
A heat exchanger consists of a bank of 1200 thin-walled tubes with air in cross flow over the tubes. Thetubes are arranged in-line, with 40 longitudinal rows(along the direction of airflow) and 30 transverserows. The tubes are 0.07 m in diameter and 2 m long,with transverse and longitudinal pitches o

Fundamentals of Heat and Mass Transfer 7
Derive the expression for the modified effectiveness?*, given in Comment 4 of Example 11.8.

Fundamentals of Heat and Mass Transfer 7
Consider Problem 3.144a.(a) Using an appropriate correlation from Chapter 8,determine the air inlet velocity for each channel inthe heat sink. Assume laminar flow and evaluateair properties at T?300 K.(b) Accounting for the increase in air temperature asit flows through the heat sink, determine the c

Fundamentals of Heat and Mass Transfer 7
Work Problem 7.29, taking into account the increasein temperature of the water as it flows through the heatsink. Properties of water are listed in Problem 7.29,along with ??995 kg/m3and cp?4178 J/kg?K. Hint:Assume the water does not escape through the uppersurface of the heat sink and that the bounda

Fundamentals of Heat and Mass Transfer 7
The heat sink of Problem 7.29 is considered for an appli-cation in which the power dissipation is only 70 W, andthe engineer proposes to use air at T??20?C for cool-ing. Taking into account the increase in temperature ofthe air as it flows through the heat sink, plot the allow-able power dissipation

Fundamentals of Heat and Mass Transfer 7
Solve Problem 8.109a using the effectiveness-NTUmethod.

Fundamentals of Heat and Mass Transfer 7
Consider Problem 7.113. Estimate the heat transferrate to the air, accounting for both the increase in theair temperature as it flows through the foam and the thermal resistance associated with conduction in thefoam in the x-direction. Do you expect the actual heattransfer rate to the air to be equal

Fundamentals of Heat and Mass Transfer 7
The metallic foam of Problem 7.113 is brazed to thesurface of a silicon chip of width W?25 mm on aside. The foam heat sink is L?10 mm tall. Air atTi?27?C, V?5 m/s impinges on the foam heat sinkwhile the chip surface is maintained at 70?C. Deter-mine the heat transfer rate from the chip. To calculatea