Có 100+ tài liệu thuộc chủ đề "Cẩm nang truyền nhiệt"
tailieu.vn Xem trực tuyến Tải xuống
3C A.10). (10.A.11). (10.A.9) and (10.A.10), respectively, at θ = θ m . (10.A.9) and (10.A.10), respectively, at θ = 0.. (10.66b–f. (10.31), dimensionless. (10.21), dimensionless. (10.15), dimensionless D tube diameter, m (ft). f lo liquid-only friction factor defined by eq. (10.72), dimensionless. f (n t ) row-number correction defined by eq. (10.91) f r fraction of root of tube...
tailieu.vn Xem trực tuyến Tải xuống
Heat Transfer . A General Correlation for Heat Transfer during Film Condensation inside Pipes, Int. Calculating the Heat Transfer Coefficient in Steam Turbine Condensers, Teploenergetika . A General Heat Transfer Correlation forAnnularFlow Condensation, J. Spencer, E., and Hewitt, E. The Heat Transfer and Pressure Drop Behavior of a Zeotropic Refrig- erant Mixture in a Microfinned Tube, M.S. The Heat Transfer...
tailieu.vn Xem trực tuyến Tải xuống
For the counterflow exchanger where the fluids flow in opposite directions through the exchanger (Fig. 11.2a),. (11.25). For the co-current or parallel flow exchanger where the fluids flow in the same direction through the exchanger (Fig. 11.2b),. (11.26). 11.2c),. (11.27). 11.2d),. (11.28) These simple expressions for the logarithmic mean temperature difference cannot be employed for arrangements other than those shown...
tailieu.vn Xem trực tuyến Tải xuống
Crossflow exchanger with fluids unmixed.. 1.00 C min max / C = 0. C min max / C = 0. Figure 11.5 Heat exchanger effectiveness as a function of N tu for 10 heat exchanger arrange- ments. Normal Page PgEnds: TEX . for C min max / C = 1. Exchanger performance effect of C min max / C. 1.0...
tailieu.vn Xem trực tuyến Tải xuống
Normal Page PgEnds: TEX Figure 11.9a shows a single-pass tube side and a baffled single-pass shell side.. A toroidal expansion joint in the center ofthe shell accommodates the differential thermal expansion between the tubes and the shell. Figure 11.9b employs U-tubes within the baffled single-pass shell. In this case, account must be taken of the fact that approximately halfofthe tube-side...
tailieu.vn Xem trực tuyến Tải xuống
A w (11.91a). N cc (11.91b). 100 (11.91c). is the crossflow area for the bypass, where N P is the number ofbypass divider lanes that are parallel to the crossflow stream B, w P is the width ofthe bypass divider lane (m), and L bc is the central baffle spacing.. J S is the correction factor that accounts for variations...
tailieu.vn Xem trực tuyến Tải xuống
Figure 11.16 Some compact heat exchanger elements. Surfaces with flow normal to banks of smooth tubes. 11.16a. Other types reduce the flow resistance outside the tubes by using flattened tubes and brazing, as indicated in Fig. 11.16b and c. 11.16d through i.. (a) The plain fin is characterized by long uninterrupted flow passages and is designated by a numeral that...
tailieu.vn Xem trực tuyến Tải xuống
Figure 11.21 Entrance and exit loss coefficients for flow through plate fin exchanger cores.. Gc (11.130). (11.129) and (11.130) are evaluated at the bulk tem- perature. Figure 11.22 Entrance and exit loss coefficients for flow through rectangular passages. The entrance and exit loss coefficients differ for the various types of passages and are plotted as functions of the parameter σ...
tailieu.vn Xem trực tuyến Tải xuống
d e (11.156). P t = 2 ( 2 n hp − 1 )ρV 2 (11.157). 11.6.6 Wall Temperature and Further Remarks. R is and the heat flux. Then, ifthe hot fluid is carried within the inner tube, the wall temperature will be. S (11.158). πd o (11.149). In the event, that the cold fluid is carried in the inner...
tailieu.vn Xem trực tuyến Tải xuống
(11.165). (11.173), the range ofpara- meters is. mm <. 49.55 mm 10.67 mm <. 26.01 mm 16.20 mm <. 20 mm <. 48 mm <. 64 0.25 mm <. 25.2 2.28 mm <. 2.50 20.32 mm <. (11.174) where. (11.174) is valid for. 176 mm <. 432 mm <. 552 mm 5.842 mm <. 19.05 mm 1 <. 254 mm...
tailieu.vn Xem trực tuyến Tải xuống
j h = C h Re y ch (11.193). Both ofthese values are listed in Table 11.5 as a function of the chevron angle β and the Reynolds number.. d e (11.194). P = ∆p ch + ∆p port (11.195). (11.195),. 11.36a, and where f ch = K p. Re z (11.197). TABLE 11.5 Kumar’s (1984) Constants for Single-Phase Heat...
tailieu.vn Xem trực tuyến Tải xuống
Artificial spray pond water 1.75–3.5 Temperature ≈ 120°C 3.5–7 Boiler blowdown water 3.5–5.3 Temperature ≈ 120–180°C 5.25–7. Closed-cycle condensate 0.9–1.75 Temperature >. 230°C 9–10.5 Closed-loop treated water 1.75 Petroleum streams. Distilled water 0.9–1.75 Lean oil 3.5. Engine jacket water 1.75 Liquefied petroleum gases 1.75–3. River water 3.5–5.3 Natural gasolene 1.75–3.5. Seawater 1.75–3.5 Rich oil 1.75–3.5. Treated cooling tower water 1.75–3.5...
tailieu.vn Xem trực tuyến Tải xuống
Wf wetted perimeter for friction Wh wetted perimeter for heat transfer W 1 wetted perimeter ofone channel. A Simplified Formula for Cross-Flow Heat Exchanger Effectiveness, J.Heat Transfer . 1–2N Shell-and-Tube Exchanger Effectiveness: A Simplified Kraus–Kern Equation, J.Heat Transfer . On the Search for New Solutions of the Single-Pass Crossflow Heat Exchanger Problem, Int.J.Heat Mass Transfer . Heat Transfer to Air,...
tailieu.vn Xem trực tuyến Tải xuống
Figure 12.1 Voltage ∆E versus temperature T measurements from a thermocouple system exhibiting hysteresis. When measuring an increase in T (continuous line), the sensitivity of the instrument is uniform and equal to 1.5 mV/°C. 12.1.3 Calibration. TABLE 12.1 Some Fixed Temperature Points Used as Standards for Defining the ITS-90. When the discrepancy (or accuracy) is uniform along the entire scale,...
tailieu.vn Xem trực tuyến Tải xuống
Figure 12.4 Graphical representation of the observed probability distribution Γ (shown as black triangles) and the Gaussian distribution Γ G (straight line) from Table 12.3.. To bring into a better perspective the meaning of the chi-square test example considered in the preceding paragraph, the probability distribution Γ and Gaussian distribution Γ G observed, presented in Table 12.3, are shown graphically...
tailieu.vn Xem trực tuyến Tải xuống
potential gradient along each conductor is dependent on the local temperature of the conductor.. (12.47), ε s1 must differfrom ε s2 for the potential generated by the two conductors to be nonzero. Figure 12.8 is the most fundamental representation of a thermocouple. (12.47)].. 12.9 can be predicted.. (12.44) forconductor1, E c − E 1. ε s 1 (T ) dT...
tailieu.vn Xem trực tuyến Tải xuống
Contributions to the Theory of Single-Sample Uncertainty Analysis, J.. Uncertainty Analysis in the Planning of an Experiment, J. Heat Transfer in Electronic Equipment. 13.1 Introduction. 13.1.1 Cooling requirements History. Present and future 13.1.2 Thermal packaging goals. 13.1.3 Packaging levels 13.2 Thermal resistances. 13.2.1 Introduction. 13.2.2 Basic heat transfer modes Conduction. 13.2.3 Chip package resistance Internal resistance External resistance Flow resistance....
tailieu.vn Xem trực tuyến Tải xuống
13.2.1 Introduction. To determine the component temperatures and temperature gradients encountered in the flow of heat within electronic systems, it is necessary to define the relevant heat transfer mechanisms and establish their governing relations. In a typical system, heat removal from active regions of the microcircuit(s) or chip(s) may require the use of several mechanisms, some operating in series and...
tailieu.vn Xem trực tuyến Tải xuống
Normal Page PgEnds: TEX suggested that when the grouping, NT/φ, where N is the numberof atomic layers in. 13.3.1 Spreading Resistance. In chip packages that provide for lateral spreading of the heat generated in the chip, the increasing cross-sectional area for heat flow in the “layers” adjacent to the chip reduces the heat flux in successive layers and hence the...
tailieu.vn Xem trực tuyến Tải xuống
Figure 13.12 Surface chemistry model of contact resistance.. 1 − Bψϕ (13.40). where k m is the thermal conductivity of the continuous phase or base polymer, ϕ the particle volume fraction, and S a shape parameter that increases with aspect ratio.. Table 13.6 provides the value of A for dispersed polymers. (13.40) can be estimated using the expression B =...