Heat thermal wheels

ASHRAE, Atlanta (1992)]. Process air stream 6, to be conditioned, passes through the adsorbent wheel, where it is dried. This is a non-isothermal process due to the release of heat of adsorption and transfer of heat from a wheel that may be above ambient temperature. The dry but heated air (7) is cooled in a heat exchanger that can be a thermal wheel. This stream (8) is further cooled, and the humidity adjusted back up to a comfort range by direct contact evaporative cooling to provide supply air. Regeneration air stream 1, which can be ambient air or exhausted air, is evaporatively cooled to provide a heat sink for the hot,... 

In the majority of installations, a flapper damper or diverter valve is employed to vary the flow across the heat exchanger to maintain a specific design temperature of the hot water or a specific steam generation rate. In some CHP designs, the exhaust gases are used to activate a thermal enthalpy wheel or a desiccant dehumidifier. A thermal wheel uses the exhaust gas to heat a rotating wheel with a medium that absorbs the heat and then transfers the heat into the incoming airflow into which the wheel is rotated. 

Traditional heat recovery included the recovery of heat fron a dryer outlet, the hot dried product, and/or the outlet gas. Typical devices for heat recovery are presented in Figure 54.5. Conventional heat exchangers have the following efficiency indices thermal wheel, 75%-90% plate exchanger, =70% heat pipe, =60% scrubber, =60% and two-section exchanger, =50%. 

FIGURE 54.5 Heat recovery systems in dryers (a) thermal wheel (b) plate heat exchanger (c) heat pipe installation (d) runaround coil (e) scrubber and (f) two-section heat exchanger. 

In this chapter in Section 3.1 we consider mechanical drives. In Sections 3.2 and 3.3 furnaces and exchangers, condensers and reboUers are considered followed by fluidized bed with coil in the bed, Section 3.4 and static mixers. Section 3.5. Direct contact systems are considered next liquid-liquid. Section 3.6 gas-liquid cooling towers. Section 3.7 gas-liquid quenchers. Section 3.8 gas-liquid condensers. Section 3.9, and gas-gas thermal wheels. Section 3.10. Heat loss to the atmosphere is described in Section 3.11. Refrigeration, steam generation and high temperature heat transfer fluids are presented in Sections 3.12 to 3.14, respectively. Tempered heat exchange systems are considered in Section 3.15. 

Operational Modes The Catalytic Recuperative Oxidizer assumes a 65% efficienct heat exchanger. The Thermal Recuperative Oxidizer assumes a 65% efficienct heat exchanger The Regenerative Catalytic Oxidizer assumes a 95% efficienct heat exchanger The Regenerative Thermal Oxidizer assumes a 95% efficient heat exchanger. The rotor concentrator wheel assumes a 6 1 concentration ratio. 

A secondary fan draws the air and forces it through the secondary heat exchanger, where the reduced air volume temperature is raised to the required desorption temperature. The preheated air is then used to desorb the air in one portion of the wheel. As the air exits the desorption section the organic concentration is approximately 10 times the concentration of the original process stream. This low volume, higher concentration stream then enters the induced draft section of a catalytic or thermal recuperative oxidizer, where the organics are destroyed. 

Thermal Conductivity. Abrasive materials may transfer heat from the cutting tip of the gram to tile bond posts, retaining the heat in a bonded wheel or coated belt, The cooler the cutting point, the harder it is. 

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