Condensation temperature distribution

Keywords thermoelectric generation water lens light condensing temperature distribution... 

Dukler Theory The preceding expressions for condensation are based on the classical Nusselt theoiy. It is generally known and conceded that the film coefficients for steam and organic vapors calculated by the Nusselt theory are conservatively low. Dukler [Chem. Eng. Prog., 55, 62 (1959)] developed equations for velocity and temperature distribution in thin films on vertical walls based on expressions of Deissler (NACA Tech. Notes 2129, 1950 2138, 1952 3145, 1959) for the eddy viscosity and thermal conductivity near the solid boundaiy. According to the Dukler theoiy, three fixed factors must be known to estabhsh the value of the average film coefficient the terminal Reynolds number, the Prandtl number of the condensed phase, and a dimensionless group defined as follows ... 

Figure 10-91B. Steam and condensate temperatures versus condenser length. Temperature distribution curve for the same multizone condenser as in Figure 10-91 A. Points A, E, and F are the same. Point B is above C, which locates the start of the wet desuperheating zone on the tube surface. (Used by permission Rubin, F. L. Heat Transfer Engineering, V. 3, No. 1, p. 49, 1981. Taylor and Francis, Inc., Philadelphia, PA. All rights reserved.)...

Rosenow WM (1956) Heat Transfer and Temperature Distribution in Laminar Film Condensation, Trans ASME, 78 1645. 

Figure 2.22 [2.6] demonstrates the method of a cooling circuit with recirculated flow An injector pump operated with just evaporated LN2 aspirates the warmer N2 coming from the condenser and feeds the mixture back in the condenser. The desired condenser temperature can be controlled by a throttle valve. To achieve a uniform temperature distribution, the gas mixture is alternately fed to one or the other end of the condenser. No results of such a system are given. 

A triple-effect evaporator is fed with 5 kg/s of a liquor containing 15 per cent solids. The concentration in the last effect, which operates at 13.5 kN/m2, is 60 per cent solids. If the overall heat transfer coefficients in the three effects are 2.5, 2.0, and 1.1 kW/m2K, respectively, and the steam is fed at 388 K to the first effect, determine the temperature distribution and the area of heating surface required in each effect The calandrias are identical. What is the economy and what is the heat load on the condenser ... 

An important requirement for such vapor pressure measurements with Knudsen cells is the temperature distribution in and around the cell. If the temperature is not homogeneous within the cell, condensation and crystallization of the vaporized species may occur in the colder regions. This was observed e.g. with gold. In other cases the orifice was reduced in diameter up to complete blockage when vaporized metals like aluminium where oxidized due to the partial pressure of oxygen. To prevent these deposits, ultra high vacuum is necessary or the use of graphite cells instead of alumina cells. 

In summary, although the influence of gas flowrate on heat transfer performance was shown to be small, it did exert a strong effect on the quantity of condensate remaining inside the heat exchanger. Liquid flowrate appeared to have a stronger influence on heat transfer performance and it was suggested that the temperature distribution over the PEEK film might have an additional effect on the condensation process. 

Latent heat associated with phase change in two-phase transport has a large impact on the temperature distribution and hence must be included in a nonisothermal model in the two-phase regime. The temperature nonuniformity will in turn affect the saturation pressure, condensation/evaporation rate, and hence the liquid water distribution. Under the local interfacial equilibrium between the two phases, which is an excellent approximation in a PEFG, the mass rate of phase change, ihfg, is readily calculated from the liquid continuity equation, namely... 

The combustion wave of an HMX composite propellant consists of successive re-achon zones the condensed-phase reachon zone, a first-stage reaction zone, a second-stage reaction zone, and the luminous flame zone. The combustion wave structure and temperature distribution for an HMX propellant are shown in Fig. 7.47. In the condensed-phase reaction zone, HMX particles melt together with the polymeric binder HTPE and form an energetic liquid mixture that covers the burning surface of the propellant. In the first-stage reaction zone, a rapid exother-... 

SocJ 30, 151-58(1960) (Recent advances in condensed media detonation) 37b) Dunkle s Syllabus (1960-1961), pp 4a 4b (Initiation of shock waves) lOa-lOg (Initiation of deflgrn and deton) p 12a (Frank-Kamenet-skii formulation) p 13b (Initiation by electric discharge) p 13f (Thermal Decomposition and Initiation of Explosives, as discussed by B. Reitzner) pp 17a to 17e (Mechanism of initiation and propagation of detonation in solid explosives) pp 17e 17f [Marlow Skidmore (Ref 31) concluded from their investigations that the problem of shock initiation is somehow related to the temperature distribution in the shock pulse and its effect on the chemical reaction rate. They used an Arrhenius type relationship for the rate increase in the frac-... 

The central thesis of the theory of the non-steady combustion of powders and explosives developed by Ya.B. in this article is the assumption of rapid readjustability of the gas phase of combustion compared to thermal changes in the condensed phase, which allows us to consider the gas phase as quasi-steady. This fundamental property of burning condensed materials allows us not only to significantly simplify the solution of the problem by reducing it to an analysis of the non-steady temperature distribution in the surface layer of the condensed material, but also not to carry out a detailed analysis of the complex structure of the combustion zone above the material (the multi-stage character of the chemical transformation, thermal decomposition, and gasification of the dispersed particles of condensed material and other processes). 

The theoretical approach to modelling frontal polymerization is based on the well developed theory of the combustion of condensed materials.255 "6 The main assumptions made in this approach are the following the temperature distribution is one-dimensional die development of the reaction front is described by the energy balance equation, including inherent heat sources, with appropriate boundary and initial conditions. Wave processes in stationary and cyclical phenomena which can be treated by this method, have been investigated in great detail. These include flame spreading, diffusion processes, and other physical systems with various inherent sources. 

Film condensation on a vertical plate may be analyzed in a manner first proposed by Nusselt [I], Consider the coordinate system shown in Fig. 9-2. The plate temperature is maintained at 7 ,. and the vapor temperature at the edge of the him is the saturation temperature TK. The him thickness is represented by <5, and we choose the coordinate system with the positive direction of. v measured downward, as shown. It is assumed that the viscous shear of the vapor on the him is negligible at y -- 8. It is further assumed that a linear temperature distribution exists between wall and vapor conditions. The weight of the fluid element of thickness dx between y and 8 is balanced by the viscous-shear force at y and the buoyancy force due to the displaced vapor. Thus... 

The numerical solution of governing equations of heat transfer for the evaporator and condenser regions allows determining the temperature distribution along the MHP axial direction. 

Fig. 16 The moisture content distribution of the fuel particles and the temperature distribution of the drying air. In this calculation the silo (height 2,0 m, width 1,0 m) is divided into 1000 calculaton cells. The moisture content of entering fuel is 60 % (wet basis). However, on the right side of the silo there is an area, where the moisture content is greater than 60% (wet basis) because of condensation.

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