handbook for heat exchangers and tube banks design

[...]... unit in W, M and M are the mass flow rates of the heating fluid and the heated fluid, respectively, in kg/s, t1 and t2 are the inlet and outlet temperatures of the heating fluid, t1 and t2 are the inlet and outlet temperatures of the heated fluid in ◦ C, cpm and cpm are the mean isobaric specific heat of both the heating and the heated fluid in J/kgK, and ηe is the actual or assumed efficiency of the heat exchange... to compute α and α (see Chap 1) D Annaratone, Handbook for Heat Exchangers and Tube Banks Design, DOI 10.1007/978-3-642-13309-1_2, C Springer-Verlag Berlin Heidelberg 2010 7 8 2 Design Computation For the computation of the heat transfer coefficient of the heated fluid it is best to refer to the arithmetic average of both inlet and outlet temperatures, whereas for the computation of the heat transfer... variable between 0.1 and 3.0 and considering ψ variable between 0.04 and 0.96 The values of χ c for types A and D or for types B and C with two passages of the external fluid are shown in Tables A.2 and A.3 The values of χ c for types A and B or for types C and D with three passages of the external fluid are shown in Tables A.4 and A.5 The values of χ c for types A and D or for types B and C with four passages... Fig 2.6 Heat exchangers with three passages of internal fluid t′ 1 t′′ 2 H 18 2 Design Computation The values of χ c for types E and F or for types G and H with two passages of the external fluid are shown in Tables A.10 and A.11 The values of χ c for type E or for type G with three passages of the external fluid are shown in Tables A.12 and A.13 The values of χ c for types E and F or for types G and H... β and ψ being equal, the value of χ c and thus of tm for types A and B (or A and D) with reference to Tables A.2, A.4, A.6 and A.8 is always lower than that for types C and D (or B and C) with reference to Tables A.3, A.5, A.7 and A.9 In addition, the increase in the number of passages of the fluid outside the tubes in types A and B (or A and D) is matched by an increase of tm , whereas in types C and. .. know, if a heating fluid at temperature t transfers heat to a heated fluid at temperature t the transferred heat by the time unit (expressed in W) is given by q = US t − t = US t (1.1) In (1.1) U is the overall heat transfer coefficient (in W/m2 K), S the surface of reference (in m2 ) and Δt the difference in temperature between the two fluids (in ◦ C) Both for heat exchangers and for tube banks the heat transfer... and to its physical and thermal characteristics, its temperature, its dynamic characteristics, as well as its geometrical characteristics of the tubes making up the bank Up to this point we assumed the temperatures of both fluids to be constant but in both heat exchangers and tube banks the heating fluid transferring heat cools down, whereas the heated fluid receiving it warms up In other words, the heat. .. the heating fluid In that case the surface of reference will be the internal one if the heating fluid runs inside the tubes, or the external one if the heating fluid hits the tubes from the outside By adopting this criterion the overall heat transfer coefficient in reference to the external surface indicated by Uo is given by Uo = 1 1 xw do 1 do + + α k dm α di D Annaratone, Handbook for Heat Exchangers and. .. computation for heat exchangers and tube banks The first one is the design calculation, consisting of the identification of the exchange surface required to obtain certain results The second one makes it possible to compute the outlet temperatures of the fluids and the transferred heat, once the exchange surface has been set This is a verification calculation, and we will discuss both 1.2 Mean Isobaric Specific Heat. .. Heat Exchangers and Tube Banks Design, DOI 10.1007/978-3-642-13309-1_1, C Springer-Verlag Berlin Heidelberg 2010 (1.2) 1 2 1 Introduction to Computation In (1.2) α and α are the heat transfer coefficients of the heating fluid and the heated fluid (in W/m2 K), respectively, xw is the thickness of the tube wall (in m), k is the thermal conductivity of the material of the tubes (in W/mK), and do , dm , di are .