Exchange of Sensible Heat

Exchange of Sensible Heat When there is no change in phase, the rate of neat transfer is no longer linear with the flow of the manipulated stream, but is a function of the mean temperature difference A Tm  

When a stream is manipulated whose flow is independently determined, such as the flow of a product or of a heat-transfer fluid from a fired heater, a three-way valve is used to divert the required flow to the heat exchanger. This does not alter the linearity of the process or its sensitivity to supply variations, and it even adds the possibility of independent flow variations. The three-way valve should have equal-percentage characteristics, and heat flow control may be even more beneficial. 

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The exchange of sensible heat between the water and the atmosphere was limited and always below 50 W/m2... 

Heat effects that cause temperatures to vary from point to point in a gas absorber are (1) the heat of solution (including heat of condensation, heat of mixing, and heat of reaction) (2) the heat of vaporization or condensation of the solvent (3) the exchange of sensible heat between the gas and liquid phases and (4) the loss of sensible heat from the fluids to internal or external coils. 

The statement has been made that a packed-column exchanger would be much cheaper than a conventional shell-and-tube type, but no figures have been presented to substantiate this. The work on the spray-column exchanger has been limited to the exchange of sensible heat and in any distillation process by far the greatest part of the heat exchanged is latent heat. There appears to be no reason why latent heat cannot also be exchanged in this manner. 

Intrinsic clothing thermal efficiency Reduction of sensible heat exchange due to wearing clothes. 

Figure 23.2 Exchange of sensible and latent heat at water-air surface...

Fresh feed from stream 1 combines with recirculated brine from stream 13 and the combined stream, 14, enters the main heat exchanger, where sensible heat is added, but no vaporization occurs because the pressure is maintained slightly above the vapor pressure. All vaporization occurs in the flash tank and the vapor is compressed and desuperheated and becomes the heating medium for the main exchanger. As only a small fraction of the brine evaporates (around 0.005) the majority is recirculated as stream 13, the remainder being discarded in 8. 

The electrolyser full power operating point in this work is taken from Stoots (2005). In the operating mode selected the cell is run adiabatically with a current density of 0.45 amp/cm2. There is a net production of sensible heat giving rise to an increase in temperature from inlet to outlet. The heat is recuperated by a heat exchanger at the exit of the cell and is used to heat the incoming reactants. 

Other than the heat of solution, heat effects that may influence absorber performance are solvent vaporization, sensible heat exchange between the gas and the liquid, and loss of sensible heat due to cooling coils or atmospheric cooling. Detailed discussion on heat effects in absorption is presented in the text by Sherwood et al. (1975). 

Watkinson, A.P. and Epstein, 1971, Particulate fouling of sensible heat exchangers. Proc. 4th Int. Heat Trans. Conf Vol. 1. Paper HE 1.6, Elsevier Science Publishers BV, Amsterdam. 

The heat transfer mode for subcooling liquid is that of sensible heat exchange. Subcooling heat transfer rates are much lower than condensation heat transfer rates for two reasons. First, sensible heat transfer coeflicients are much lower than condensation coeflicients and second, as the liquid subcools, the temperature difference between the... 

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