换热器热力学计算中平均温差计算方法

1、291Vol. 29 No 1Feb. 2008Nuclear Power Engineering10291Vol. 29 No 110291Vol. 29 No 10258-0926(2008)01.0076.0510291Vol. 29 No 110291Vol. 29 No 11.200030LMTD1TK124A(-NTU)LMTDD 3(LMTD)GranrydR32/R134aLN1TDPShao4 Ziegler200641.212007-034)5(50476015)1 2150001(LMTD)6LMTD卩 53 Ram LhfTDLMTDnevv叨LMTD2A> M-

2、Af“、fi AzinATMxn(2)10771 f A5 J严)c#_1 r A= i /h(x)“Ajo1 f A(l= Adq =jtA/vdAJ0Jo=kANAm2 tKkW/(m2 -】Q iKtK c1w#“amcItInLhfTD(4)tfin(3)(4)(3)(4)7(4)k(1)1131I+ 九hi(5 a)(2)1 _ 1 k ho(5b)LMTD(5a)(5b)k1151(6a)r九】iIn 厶 d° 1(6b)F-1总 G =工 Qmhq 、(8)dm,m hW/(m3 K),W/(m-K)1 0wf3(1)B303Y0 112 93 mmxl.5 mm3 0

3、8 mm,1 500 mm60 802123/?x>5x104D-BNu、= 0 023Re °3Pr°3Nih(9)lh(10)rkk- qCDA兀(10)(ID(6b)/qIh#79内背B：热电偶 位置助片外管B热电徊安装方式定位支撑结构CO)卜 _ (E _ B) “WO 'toz = +_ 当(19)(20)LMTD1Fig 1 Structure ofTest Section60= A(iJ- ffo )(12)80Re<30045 76%<z<78.55%(13)Nitham10°(14) o 6OT： LN I Drt

4、； o 6OT测空湿 A 80X LNTD法 p WH：测坚温2Experimental Results of Honzontal Flowa嗒直向上流动MWT.3 o盟安向上流动LMTD »b盟克向下流动MWTv竪宜向下流动I MTD0P(16a)icr10lIn:dj(16b)IO2IO1ReIO1(16a)(16b)(15)gam 二山ln+Ag -心 o,ln h - 心(17)woFig 33Expenmental Results of Vertical FlowRe<3006021 2345.87%<z<73.81%#LMTDLL4TD(3) RamLh

5、lTDRe 300RamLhfTD098 1%z>96 9%卩#3 82%3LMTDLNITDRam叨z严+(M严了 3 rim r Re<3Q0 (21)LMTD0 25%2 08%屉 >300011%CD4(1) LMTD(2)LMTDRe<30Q45 76%V<78 55%LMTD1 Chou J P Experimental Investigation of tlie Augmenta- ticn of Forced Convection Heat Transfer in a Circular Tube Using Spiral InsertsJ Jour

6、nal of Heat Transfer. 1987, 109(5): 300 3072 Panchai C B» France D M, Bell K J Experimental Investigation of Single-Phase Condensation and Flow Boiling Heat Transfer for a Spirally Fluted TubeJ Heat Transfer Engineenng, 1992, 13(1): 42 513J2004, 1: 52 55.(21)4 Shao D W, Granryd E Experimental a

7、nd TheoreticalStudy on Flow Condensation with Non-Azeotropic Refrigerant Mixtures of R32/R134aJ Int J Refig, 1998, 21(3): 230 246J.1990, 5(2): 169170.6 Ziegler Felix Relationships between Temperature Differences in Heat Exchangers of Heat Transformation De- vicesJ Revue Generale de Thermique, 199&am

8、p; 37(7) 549 555.7J., 1997.18(4): 325 331.JI. 1991, 15(3): 8 219 Ram Prasad An Improved Approved Approximation for the Log-Meaii Temperature DifferenceJ Cheixucal En- gineenng 198& 95(14): 110.(10 ()M.1987,357 391.Investigation on Calculation Method of Mean TemperatureDifferenee in Heat Exchange

9、Thermodynamic CalculationLU Guang-yao1, WANG Jing1, SUN Zhong-iiing21 School of Mechanical Engineering Shanghai Jiaotong Uiurereity Shanghai, 200030, Chuia2 College of Power and Nuclear Engineeiing. Haibm Engmeenng Uiuvemty Haibin, 150001, ClunaAbstract: The calculation method for the logarithm irea

10、n temp mature difference (LMTD) and tlie anthmetic temperature difference was analyzed Heat exchange is calculated by two methods of loganthm mean temperature difference and measuring of wall temperature, and calculation results were analyzed Ex 81Vol. 29 No. 1 2008periment showed that in the calcul

11、ation of the convective heat transfer coefficient, the results gained by these two methods had large differences, especially in low Reynolds number region The difference of the calcula tion results came from the distinctness between LK1TD and AlvfTD Ill the turbulent flow area, the difference became

12、 small and LMTD can be adopted to analyze the convective heat transfer characteristics in the tui'bu- lent flow area in the engineering calculationKey words Heat exchanger, Logarithm mean temperature difference, Arithmetic mean temperature difference. Measuring of wall temperature(1978)2004(1945

13、)1993(1963)2000(52)1 Jinmei Tiant Yufeng Xing The Frequencies of Two- Dimensional Laminated Beam by Several Laminated Composite ModelsC, WCCM VI in Conjunction witli APCOW04, Beijing, 20042 M.,1993.3 Reddy J N Energy and Vanational Methods in Applied MechamcsM The United States of America, JOHN WILE

14、Y &SONS. Inc. 1984.#Vol. 29 No. 1 2008#Vol. 29 No. 1 2008Comparison of Beam Element and Shell Element inAnalyzing Inherent Vibration of StructuresTIAN Jin-mei(Beijing Institute of Nuclear Engineeiing, Beijmg, 100840, China >Abstract： Finite element models of tube structures are set up using A

15、NSYS with beam 188 element and shell63 element respectively The computing programs are written by means of APDL language, the fi'ee vibration characte门sties of tube structures with lengtli-to-dianieter ratios of 420 are computed Also, the corresponding inherent fi'equencies and modes are analyzed The results show that as to tube structures with lengtli-to-diametei' largei* than 10, the beam element of ANSYS based on Timoshenko beam can meet our requirements, but as to tube stnictures with lengthtodiameter smaller than 6, in order to nnprove th