Heat exchangers reversing

If q is the heat exchanged reversibly per mole of the substance during the phase transformation at temperature T, then the change of entropy (AS) in this process is given by AS = q/T dP q... 

Thus in addition to the data required to determine the surface excess amount (cf. Section 3.3.1), one needs to know dQKV (the heat exchanged reversibly during each adsorption step) and Vc (the volume - dead space - of that part of the adsorption bulb which is located within the calorimetric detector (cf. Figure 3.15). Vc is evaluated by liquid weighing or by geometrical considerations and corrected for the sample volume. 

Figure 5.1 Simplified heat exchanger. Reversible operation requires infinitely slow liquid movement the outgoing liquid then has the same temperature as the inlet water.

As noted earlier, the approximations for both the heat transfer and the pressure drop are dependent upon the type of geometry used in the heat exchanger. Reversing heat exchangers, when used in air separation plants, are normally subjected to one million pressure reversals over a 15-20-year life... 

Continuous recuperative furnaces employing metallic recuperators (heat exchangers) have been in use since the 1940s. Operation of these furnaces is simplified and the combustion process is more precisely controlled no reversal of air flow causes temperature variations. The recuperator metal must be caretiiUy selected because of chemical attack at high temperature. Recuperative furnaces are often used in the production of textile fiber glass because they maintain a constant temperature. 

In open fibers the fiber wall may be a permselective membrane, and uses include dialysis, ultrafiltration, reverse osmosis, Dorman exchange (dialysis), osmotic pumping, pervaporation, gaseous separation, and stream filtration. Alternatively, the fiber wall may act as a catalytic reactor and immobilization of catalyst and enzyme in the wall entity may occur. Loaded fibers are used as sorbents, and in ion exchange and controlled release. Special uses of hoUow fibers include tissue-culture growth, heat exchangers, and others. 

Hardness Calcium, magnesium, barium and strontium salts expressed as CaCOa Chief source of scale in heat exchange equipment, boilers, pipe lines, etc. forms curds with soap interferes wKh dyeing, etc. Softening, distillation, internal boiler water treatment, surface active agents, reverse osmosis, electrodialysis... 

We adopt the nomenclature introduced by Hawthorne and Davis [1], in which compressor, heater, turbine and heat exchanger are denoted by C, H, T and X, respectively, and subscripts R and I indicate internally reversible and irreversible processes. For the open cycle, the heater is replaced by a burner, B. Thus, for example, [CBTX]i indicates an open irreversible regenerative cycle. Later in this book, we shall in addition, use subscripts... 

In the ultimate version of the reheated and intercooled reversible cycle [CICICIC- HTHTHT- XJr, both the compression and expansion are divided into a large number of small processes, and a heat exchanger is also used (Fig. 3.6). Then the efficiency approaches that of a Carnot cycle since all the heat is supplied at the maximum temperature Tr = T ax and all the heat is rejected at the minimum temperature = r,nin. 

The nomenclature introduced by Hawthorne and Davis [4] is adopted and gas turbine cycles are referred to as follows CHT, CBT, CHTX, CBTX, where C denotes compressor H, air heater B, burner (combustion) T, turbine X, heat exchanger. R and I indicate reversible and irreversible. The subscripts U and C refer to uncooled and cooled turbines in a cycle, and subscripts 1,2, M indicate the number of cooling steps (one, two or multi-step cooling). Thus, for example, [CHT] C2 indicates an irreversible cooled simple cycle with two steps of turbine cooling. The subscript T is also used to indicate that the cooling air has been throttled from the compressor delivery pres.sure. 

In the amine regenerator, the rich amine solution is heated to reverse the acid-base reaction that takes place in the contactor. The heat is supplied by a steam reboiler. The hot, lean amine is pumped from the bottom of the regenerator and exchanges heat with the rich amine in the lean-rich exchanger and a cooler before returning to the contactor. 

Transfer of heat through the walls of the evaporator and condenser requires a temperature difference, and the larger these heat exchangers are, the lower will he the temperature differences and so the closer the fluid temperatures will he to those of the load and condensing medium. The closer this approach, the nearer the cycle will he to the ideal reversed Carnot cycle. (See Table 2.1.)... 

Response time constant 403 Rkster. S. 6-13,655 Return bends, heat exchanger 505 Reversed flow 668 Reversibility, isothermal flow 143 Reversible adiabatic, isentropic flow 148... 

The reverse flow reactor (RFR) concept was originally patented by Cottrell in 1938 [64] in the United States and further developed and appHed to different purposes by several researchers, for example, Matros and coworkers [65]. This technology has found its application also in the field of catalytic oxidation [66]. The incinerator containing two sets of regenerative-type heat exchangers and at least two catalyst honeycombs uses flow reversal to recover the heat produced in exothermal oxidation reactions [67]. A regenerative heat exchanger can typically achieve a heat... 

For reversible adiabatic expansion (no heat exchange with the surroundings) ... 

Ion exchange Reverse osmosis Nano-filtration Electro dialysis Crystallization Evaporation Acid Base Heat treatment UV light Chemical oxidation... 

This cycle also uses continuous counterflow heat exchanger and is closely related to the Joule-Thomson and Claude cycles as shown in Fig. 5.15(a) [60], The cryocooling or reverse Brayton cycle derives from a reciprocating gas engine patented by G. B. Brayton in... 

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