Application in Heat Exchangers

With no moving parts to generate heat, static mixers are adaptable for melt cooling heat exchangers, for example in foam extrusion. The division and re-orientation exposes polymer from the centre to the cooled outer surface. At the same time the design needs to be selected to minimise pressure drop as otherwise back pressure will cause more heat to be generated by the extruder screw. 

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Atomic power production The necessity for avoiding contamination of operative liquids, together with other requirements which must be met in selecting constructional materials in this highly specialised field has resulted in the choice of austenitic steels for applications in heat exchangers, pressure vessels, pipelines and fuel processing. 

Copper itself is not considered a structural material because of its high density and unsatisfactory mechanical properties. However, graphite fibres, which increase thermal conductivity and reduce CTE and density, provide the composite with favourable properties for application in heat exchangers, radiators and electronics. 

Hardness Calcium and magnesium salts in the forms of CaCOj, Ca, Mg. This is the primary source of scaling in heat exchange equipment, boilers, pipelines/transfer lines, etc. Tends to form curds with soap and interferes with dyeing applications as well. 

Swedish iron is sometimes used as galvanic wastage plates in heat exchangers, particularly for marine applications. This is possibly based on tradition, since it cannot be the most economical method in the light of current cathodic-protection practice. The material is not currently used as an impressed-current anode. 

Herd, K. G., W. P. Goss, and J. W. Connell, 1983, Correlation of Forced Flow Evaporation Heat Transfer Coefficient in Refrigerant Systems, Paper B2, in Heat Exchangers for Two-Phase Applications, Vol. 27, National Heat Transfer Confi, Seattle, WA. (4)... 

Robertson, J. M., 1983, The Boiling Characteristics of Perforated Plate-Fin Channels with Liquid Nitrogen in Upflow, in Heat Exchangers for Two-Phase Flow Applications, ASME HTD-Vol. 27, pp. 35-40. (4)... 

Process gases leaving the steam reformer are at temperatures of about 1580°F to 1,620°F (860°C to 880°C). This heat is recovered in heat exchange systems for use in boilers and overall process applications. 

Throughout the chemical industry, titanium is used extensively both in plant and in laboratory. Among important present-day applications are heat exchangers, autoclave heads, autoclave coils for cooling and heating, chemical processing racks, and valves and tanks where corrosion resistance is necessary,... 

In heat exchanger applications, cascade loops are configured so that the master detects the process temperature and the slave detects a variable, such as steam pressure, that may upset the process temperature. The cascade loop, responds immediately and corrects for the effect of the upset before it can influence the process temperature. The cascade master adjusts the set point of the slave controller to assist in achieving this. Therefore, the slave must be much faster than the master. A rule of thumb is that the time constant of the primary controller should be ten times that of the secondary, or the period of oscillation of the primary should be three times that of the secondary. One of the quickest (and therefore best) cascade slaves is the simple and inexpensive pressure regulator. 

Applications of heat exchangers include air conditioning systems and car/ truck radiators, but they are also widely employed in the process industry whenever there is a need for cooling or heating up a process fluid. 

Bejan, A., "The Concept of Irreversibility in Heat Exchanger Design Counter-flow Heat Exchangers for Gas-to-Gas Applications," Trans. ASME J. Heat Transfer, 99, 374 (1977). 

In oil and gas refinery applications, titanium is used as protection in environments of H2S, S02, C02, NH3, caustic solutions, steam, and cooling water. It is used in heat-exchanger condensers for the fractional condensation of crude hydrocarbons, NH3, propane, and desulfurization products using seawater or brackish water for cooling. 

In heat-exchanger applications, it is frequently important to match heat-transfer requirements with pressure-drop limitations. Assuming a fixed total heat-transfer requirement and a fixed temperature difference between wall and bulk conditions as well as a fixed pressure drop through the tube, derive expressions for the length and diameter of the tube, assuming turbulent flow of a gas with the Prandtl number near unity. 

Yang, Z. "Application of Heat Exchange by Gas-Solid Dilute Fluidization in Cement Industry (Chinese), The Proceeding of 2nd National Conference on Fluidization, pp. 349-350 (1980). 

Equation (40) shows that the optimum hydraulic diameter decreases at lower temperatures. Thus, microscale effects may be more important in low temperature applications, such as in heat exchangers of cryocoolers. However, temperature has little effect on the relative importance of slip flow. The mean free path of gas molecules is given by... 

In the applications, industrial heat exchanges are mini-and-microscale heat transfers, miniature and micro heat pipes and heat transfer issues in cryogenic catheters are presented. Nanotechnology and heat transfer including heat transfer characteristics of silicon film irradiated by pico to femtosecond lasers are also introduced and discussed. 

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