[7] Gužela Š., Dzianik, F. “Some facts resulting from the key variables used in the description of the recuperative heat exchangers”, Strojnícky časopis – Journal of Mechanical Engineering 68 (3), pp. The exhaust heat from the turbine is used to pre-heat the air from the compressor before further heating in the combustor, reducing the fuel input required. To accomplish this the hot fluid is brought into contact with the heat storage medium, then the fluid is displaced with the cold fluid, which absorbs the heat. In some special cases, it is not necessary to know its operating characteristic to calculate the heat exchanger. Recuperative heat exchangers employ either direct contact or indirect contact transfer processes to exchange heat between fluids. The results of the numerical simulation are validated with the corresponding experimental measurements. ScienceDirect ® is a registered trademark of Elsevier B.V. ScienceDirect ® is a registered trademark of Elsevier B.V.
In direct contact heat exchangers , the fluids are not separated within the device and heat transfers from one fluid to another through direct contact. https://doi.org/10.1016/S1359-4311(01)00050-3. Generally, they are used to extract heat from the exhaust and use it to preheat air entering the combustion system. By continuing you agree to the use of cookies. Despite a corresponding absorption of latent heat, as some of the water film is evaporated in the opposite airstream, the water will reduce the thermal resistance of the boundary layer of the heat exchanger material and thus improve the heat transfer coefficient of the device, and hence increase efficiency. The Recuperative Heat Exchangers ... To calculate the heat exchanger, it is important to know the type of heat exchanger and its operating characteristic. In this manner heat from the exhaust air stream is transferred through the separating plates, and into the supply air stream. The term recuperator refers as well to liquid-liquid counterflow heat exchangers used for heat recovery in the chemical and refinery industries and in closed processes such as ammonia-water or LiBr-water absorption refrigeration cycle. This characteristic determines one of the key variables (e.g., F, NTUmin, or θ). Read more. [6] Gužela Š., Dzianik F., Juriga M., Kabát J.: “Shell and tube heat exchanger - The heat transfer area design process”, Strojnícky časopis – Journal of Mechanical Engineering 67 (2), pp. 259 – 264. Devices typically comprises a series of parallel plates of aluminium, plastic, stainless steel, or synthetic fiber, alternate pairs of which are enclosed on two sides to form twin sets of ducts at right angles to each other, and which contain the supply and extract air streams. [3] Mueller A. C., in Rohsenow W. M., Hartlett J. P. “Handbook of heat transfer”, Sec. [4] Roetzel W., Spang B. “Procesy a zariadenia 1”, 1. The article also contains a general dependency that allows checking the key variables related to a given heat exchanger. However, a closer investigation finds it usable in a … Assuming the fans are fitted with inverter speed controls, set to maintain a constant pressure in the ventilation system, then the reduced pressure drop leads to a slowing of the fan motor and thus reducing power consumption, and in turn improves the seasonal efficiency of the system. As a general rule a recuperator selected for a pressure drop of between 150–250 pascals (0.022–0.036 psi) will have a good efficiency, while having a small effect on fan power consumption, but will have in turn a higher seasonal efficiency than that for physically smaller, but higher pressure drop recuperator. as a recuperative heat exchanger or simply as a recuperator. The evaluation is based on a theoretical model of the Hampson-type counter-flow heat exchanger. [1] Bowman R. A., Mueller A. C., Nagle W.M. [2] Kays W. M., London A. L. “Compact heat exchangers”, 2nd ed., New York, McGraw-Hill Book Co., 1964. 259 – 264, 1990. Preliminaries The proposed heat exchangers might be surprinsing for specialists, because it is made with concrete, a material considered unsuitable for gas-to-gas heat exchangers.
The liquefied fraction y of the working gas can be derived applying the first law to the recuperative heat exchanger, throttling jet and liquid reservoir. A heat exchanger is a device that is used to transfer thermal energy (enthalpy) between two or more fluids, between a solid surface and a fluid, or between solid particulates and ... as a recuperative heat exchanger or simply as a recuperator. [7] Gužela Š., Dzianik, F. “Some facts resulting from the key variables used in the description of the recuperative heat exchangers”, Strojnícky časopis – Journal of Mechanical Engineering 68 (3), pp. “Vefbessertes Giagramm zur Berechnung von Wänneüberttragern”, Wärme-unf Stoffübertragung, 25, pp. Thermodynamics: An Engineering Approach, Learn how and when to remove this template message, https://en.wikipedia.org/w/index.php?title=Recuperator&oldid=962723538, Creative Commons Attribution-ShareAlike License, This page was last edited on 15 June 2020, at 17:48. {Some examples of direct-transfer type heat exchangers are tubular, plate-type, and extended surface exchangers. ISBN 80-967064-3-8 (in Slovak), [10] Lodes A., Langfelder I. [6] Gužela Š., Dzianik F., Juriga M., Kabát J.: “Shell and tube heat exchanger - The heat transfer area design process”, Strojnícky časopis – Journal of Mechanical Engineering 67 (2), pp. [11] Schneller J., Hlavačka V. “Význam termickej účinnosti při výpočtech jednoduchých i složitějších teplosměnných systémů”, Strojírenství 6 (22), Strojnícky časopis - Journal of Mechanical Engineering. Recuperators can be used to increase the efficiency of gas turbines for power generation, provided the exhaust gas is hotter than the compressor outlet temperature. Whereas in recuperators, where heat is transferred directly and immediately through a partition wall of some kind, from a hot to a cold fluid, both of which flow simultaneously through the exchanger, the operation of the regenerative heat exchanger involves the temporary storage of the heat transferred in a packing which possesses the necessary thermal capacity. To learn more about the use of cookies, please read our. [2] The major practical challenge for a recuperator in microturbine applications is coping with the exhaust gas temperature, which can exceed 750 °C (1,380 °F).

[5] Jelemenský K., Šesták J., Žitný R.: “Tepelné pochody”, 2. vydanie, Bratislava: Vydavateľstvo STU v Bratislave. The simulation model provides a useful tool for miniature J–T cooler design. Examples of recuperative heat exchangers are boilers, heaters, coolers, vaporizers, condensers etc. 13 – 24, 2017. A Recuperative Heat Exchanger has separate flow paths for each fluid and fluids flow simultaneously through theexchanger exchanging heat across the wall separating the flow paths. The two major types of primary heat recovery are Recuperative and Regenerative heat exchanger systems. ISBN 80-05-00150-9 (in Slovak), [11] Schneller J., Hlavačka V. “Význam termickej účinnosti při výpočtech jednoduchých i složitějších teplosměnných systémů”, Strojírenství 6 (22), 1972. “Mean temperature difference in design”,, ASME Transaction 62, 1940. A recuperator is a heat exchanger that extracts heat from the furnace waste gases to preheat the incoming combustion air. “Procesy a zariadenia 1”, 1. A recuperator is a special purpose counter-flow energy recovery heat exchanger positioned within the supply and exhaust air streams of an air handling system, or in the exhaust gases of an industrial process, in order to recover the waste heat.Generally, they are used to extract heat from the exhaust and use it to preheat air entering the combustion system. (in Slovak). 1 – 113. Compared to alternatives such as regenerative furnaces, initial costs are lesser, there are no valves to be switching back and forth, there are no induced-draft fans and it does not require a web of gas ducts spread up all over the furnace. MAXIMUM EFFICIENCY. [4] Roetzel W., Spang B. The heat exchangers are used to heat or cool the material streams. However, the film of condensation will also slightly increase pressure drop through the device, and depending upon the spacing of the matrix material, this can increase resistance by up to 30%. Recuperators are often used in association with the burner portion of a heat engine, to increase the overall efficiency. ROTARY HEAT EXCHANGER. In this way they use waste energy to heat the air, offsetting some of the fuel, and thereby improves the energy efficiency of the system as a whole. We use cookies to help provide and enhance our service and tailor content and ads. When heat recovery is not required, it is typical for the device to be bypassed by use of dampers arranged within the ventilation distribution system. A Regenerative Heat Exchanger has a single flow path, which the hot and cold fluids alternately pass through.

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