Internal heat transfer

F. Kreith, Principles of Heat Transfer, International Educational Pubhshers, New York, 1973. 

In every case, as expected by theory, larger particle sizes produced greater solid concentration slopes. In the 30.5 cm column, no effect from the heat transfer internals on solid concentration profiles was observed for any of the three size ranges studied. 

Guo, Z.Y. and Li, Z.X., Size effect on microscale single-phase flow and heat transfer. International Journal of Heat and Mass Transfer, vol. 46, pp. 59-149, 2003. 

Hargrave, G. K., Fairweather, M., and Kilham, J. K. "Forced Convective Heat Transfer from Premixed Flames—Part 2 Impingement Heat Transfer." International Journal of Heat and Fluid Flow 8, no. 2 (1987) 132-38. 

Viskanta, R. "Convective and Radiative Flame Jet Impingement Heat Transfer." International Journal of Transport Phenomena 1 (1998) 1-15. 

Baukal, C. E., and Gebhart, B. "A Review of Semi-Analytic Solutions for Flame Impingement Heat Transfer." International Journal of Heat and Mass Transfer 39, no. 14 (1996) 2989-3002. 

Once the short power is reduced to zero at 1,410 s, the cell temperature quickly becomes uniform, as heat transfer internal to the cell equalizes the temperature within the cell. 

Recuperator Internal Area Reliability scaled to internal area. Failures would need to be sufficiently large to impact heat transfer. Internal leak (fails). 9963 per HX (.9953 - 200 kW HX)... 

Kern, D.Q., Process Heat Transfer, International edition, McGraw Hill, Singapore, 1988. 

Ga.s-to-Pa.rticle Heat Transfer. Heat transfer between gas and particles is rapid because of the enormous particle surface area available. A Group A particle in a fluidized bed can be considered to have a uniform internal temperature. For Group B particles, particle temperature gradients occur in processes where rapid heat transfer occurs, such as in coal combustion. 

Another design, shown ia Figure 5, functions similarly but all components are iaside the furnace. An internal fan moves air (or a protective atmosphere) down past the heating elements located between the sidewalls and baffle, under the hearth, up past the work and back iato the fan suction. Depending on the specific application, the flow direction may be reversed if a propeUer-type fan is used. This design eliminates floorspace requirements and eliminates added heat losses of the external system but requires careful design to prevent radiant heat transfer to the work. 

Correlations for Convective Heat Transfer. In the design or sizing of a heat exchanger, the heat-transfer coefficients on the inner and outer walls of the tube and the friction coefficient in the tube must be calculated. Summaries of the various correlations for convective heat-transfer coefficients for internal and external flows are given in Tables 3 and 4, respectively, in terms of the Nusselt number. In addition, the friction coefficient is given for the deterrnination of the pumping requirement. 

D. P. Colvin, J. C. Mulligan, and Y. G. Bryant, Enhanced heat transfer in environmental systems using microencapsulatedphase change materials, 22nd International Conference on Environmental Systems, 1992. U.S. Pat. 4,807,696, D. P. Colvin and J. C. Mulligan (1989). 

P. Vin2 and C. A. Busse, "Axial Heat Transfer Limits of Cylindrical Sodium Heat Pipes Between 25 W/cm and 15.5 kW/cm, " International Heat Pipe Conference, Stuttgart, Germany, 1973. 

Commonly used heat-transfer surfaces are internal coils and external jackets. Coils are particularly suitable for low viscosity Hquids in combination with turbine impellers, but are unsuitable with process Hquids that foul. Jackets are more effective when using close-clearance impellers for high viscosity fluids. For jacketed vessels, wall baffles should be used with turbines if the fluid viscosity is less than 5 Pa-s (50 P). For vessels equipped with cods, wall baffles should be used if the clear space between turns is at least twice the outside diameter of the cod tubing and the fluid viscosity is less than 1 Pa-s (10... 

P). Otherwise the baffles should be located iaside the cod helix. A conventional jacket consists of a vessel outside the main vessel with a gap for the flow of heat-transfer fluid. Half-pipe jackets are usefld for high pressures up to 4 MPa (600 psi). They are better for Hquid than for vapor service fluids and can be easdy 2oned. Dimple jackets are suitable for larger vessels and process conditions up to 2 MPa (300 psi) and 370°C. Internal cods can be either hehcal or baffle cods (Fig. 34). 

Fig. 34. Internal cod configurations for heat-transfer surfaces (a) hehcal cod where = 0.02T, = 0.15T, and = 0.65Z (b) baffle cod...

Fig. 35. Correlations for calculating heat-transfer coefficients for (a) turbine external jackets, internal cods, and baffle cods, and (b) for close-clearance...

L. W. Florschuetz and A. R. Khan, Fourth International Heat Transfer Conference, Paris, Prance, 1970. 

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