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Plants and Equipment
Published in Kenneth E. Heselton, Boiler Operator’s Handbook, 2020
There’s a general use of the term heat trap to refer to anything that is added to a boiler to absorb heat remaining in the flue gas. They normally return that heat directly to the boiler. Conventional heat traps are economizers and air preheaters. Condensing heat exchangers can be used as either an economizer or air preheater but are commonly used to heat water for other purposes.
Plants and Equipment
Published in Carl Bozzuto, Boiler Operator's Handbook, 2021
There is a general use of the term “heat trap” to refer to anything that is added to a boiler to absorb heat remaining in the flue gas. They normally return that heat directly to the boiler. Conventional heat traps are economizers and air preheaters. CHXs can be used as either an economizer or an air preheater but are commonly used to heat water for other purposes.
Implications of stubble management on snow hydrology and meltwater partitioning
Published in Canadian Water Resources Journal / Revue canadienne des ressources hydriques, 2019
Phillip Harder, John W. Pomeroy, Warren D. Helgason
Studies relating stubble and snowmelt have focused on observing the infiltration and runoff responses rather than differences in melt rates or changes to the snowmelt energy balance (Elliot and Efetha 1999; Nicholaichuk and Gray 1986; Granger, Gray, and Dyck 1984; van der Kamp et al. 2003). The primary influence of stubble on the snowmelt process is that it defines the amount of accumulated SWE to be melted, as described in the previous section. Observations by Willis et al. (1969) showed earlier and more rapid snowmelt in stubble plots and it was hypothesized that this was due to stubble conducting more heat into the snowpack, intercepting and absorbing more solar radiation than snow, reflecting energy to the snowpack and providing an effective heat trap against convection. Exposed stubble in snow was also identified as a potential heat sink during the melt period by Nicholaichuk and Gray (1986). Harder et al. (2018) describe the development of a stubble-snow-atmosphere model (SSAM) which accounts for stubble characteristics (exposed stubble height, stalk width, row spacing, and stalk density) and quantifies all components of the snow surface energy balance below an exposed stubble. Compensatory processes are revealed from observation and model results. Specifically, shortwave radiation is attenuated as it passes through stubble, longwave transmission to the snow surface is enhanced from emissions from warm stalks, and turbulent fluxes have a more complex response to stubble exposure. Overall, the longwave, shortwave and turbulent terms largely compensate, resulting in a negligible, but variable, change in energy with stubble exposure (Harder et al. 2018).