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Figure 4-13aSource: Kelvion, www.flatplateselect.comFigure 4-13b44
Figure 4-13cthe minimum surface area required for the specified heatexchange rate. In some cases, the extra surface area isnecessary to limit the pressure drop of one or both sides ofthe heat exchanger. The software provides performancedata such as the overall heat transfer coefficient, flowvelocity and rate of heat transfer. Physical data onthe candidate heat exchangers, including volume anddimensions, are also listed. The ability of this softwareto evaluate several “what if” scenarios in a fraction ofthe time required for manual calculations makes it anessential design tool.HEAT EXCHANGER PERFORMANCE INDICESTwo indices are commonly used to describe the actualperformance, or performance target, of heat exchangers.They are:• Approach temperature difference• Thermal lengthApproach temperature difference is the temperature of thefluid entering the hot side of the heat exchanger, minus thetemperature of the “cooler” fluid leaving the heat exchanger.Figure 4-14 illustrates this difference.the previous examples — is estimating the values for theconvection coefficients (h h and h c ) in Formulas 4-7 and 4-9.Those calculations are often iterative and time consuming.As such, they don’t lend themselves to repeated “what if”scenarios when a designer is trying to select an appropriateheat exchanger.Many manufacturers now offer software that can rapidlyevaluate the necessary mathematics for sizing andselection of their heat exchangers. In some cases, thissoftware is accessed online. In other cases, it’s necessaryto download and install the software. Some suppliers alsorequire submittal of design parameters and operate thesoftware in-house.A theoretically infinite heat exchanger would have anapproach temperature difference of 0. Any real heatexchanger will have an approach temperature differencegreater than zero. Some brazed plate and plate & frameheat exchangers can operate at approach temperaturedifferences as low as approximately 2ºF, although thisFigure 4-14Approachtemperature =differenceT hot in( )T hot in- T cool outT cool outOne example of online-based sizing and selection softwareis FlatPlateSELECT, available at http://flatplateselect.com/site/hx/chooseapp.aspx. Figures 4-13a, b and cshow some examples of this software.Some heat exchanger sizing and selection softwareproduces a list of several specific models that can meetthe requirements based on input data. They also show an“oversurface” percent, which is the percent by which thesurface area in the suggested heat exchanger exceedsT hot outT cool in45
Page 1 and 2: TMJOURNAL OF DESIGN INNOVATION FOR
Page 3 and 4: FROM THE GENERAL MANAGER & CEODear
Page 5 and 6: 1. INTRODUCTIONOne of humankind’s
Page 7 and 8: Figure 1-6 Figure 1-8Figure 1-9Figu
Page 9 and 10: Figure 2-4supplemental / auxiliary
Page 11 and 12: Figure 2-6solar thermalcollector ar
Page 13 and 14: Courtesy of Hydroflex Systems, Inc.
Page 15 and 16: Figure 2-15Figure 2-16Courtesy of B
Page 17 and 18: Courtesy of (a) Alfa Laval, and (b)
Page 19 and 20: Figure 2-24Courtesy of Alfa LavalLa
Page 21 and 22: how to account for plate thickness
Page 23 and 24: Figure 2-33Notice that the directio
Page 25 and 26: Figure 2-36Greywater heat exchanger
Page 27 and 28: 3. HEAT TRANSFER FUNDAMENTALSTwo fu
Page 29 and 30: Figure 3-3Heat output (Btu/hr/ft)60
Page 31 and 32: process. The value of (h) varies wi
Page 33 and 34: 4. THERMAL CHARACTERISTICS OF HEAT
Page 35 and 36: ( )q sAF T 4 4− T12 1 2⎡ 1 q =+
Page 37 and 38: 0.00032 ft ⋅sec( ) 1− ( ∆T )
Page 39 and 40: Figure 4-9enters the secondary side
Page 41 and 42: Figure 4-11FINNED-TUBE BASEBOARDout
Page 43: CC ratio= C ratio min= C minC maxC
Page 47 and 48: absorbing heat. The latter is a muc
Page 49 and 50: which to release its heat. However,
Page 51 and 52: 5. INSTALLATION DETAILS FOR HEAT EX
Page 53 and 54: Figure 5-4aFigure 5-5isolation /pur
Page 55 and 56: Figure 5-8temperature sensorsetpoin
Page 57 and 58: 6. HEAT EXCHANGER APPLICATIONSThis
Page 59 and 60: Figure 6-3a Figure 6-3bCourtesy of
Page 61 and 62: Figure 6-5to/fromspace heatingloadb
Page 63 and 64: Courtesy of Diversified Heat Transf
Page 65 and 66: Figure 6-10isolation / flush valves
Page 67 and 68: Courtesy of Diversified Heat Transf
Page 69 and 70: Figure 6-14modulating /condensingbo
Page 71 and 72: Figure 6-15multiple boilerstaging &
Page 73 and 74: Figure 6-17an existing boiler that
Page 75 and 76: Figure 6-19pipingbelowfrost lineret
Page 77 and 78: Figure 6-22air handlersbalancingzon
Page 79 and 80: APPENDIX B: CALEFFI PLUMBING COMPON

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