Complete Plumbing and Central Heating Guide by Jacson, Day

By Jacson, Day

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Flow work. This is the energy transferred into or out of a system by the fluid flowing into or out of it. Heat is a form of energy, specifically thermal energy. Heat transfer requires a temperature difference, and the higher the temperature difference, the greater the heat transfer rate. Thermal energy flows only from a higher temperature level to a lower temperature unless external energy is added to force the opposite to occur. If there is no heat transfer involved in a process, it is called adiabatic.

All real processes are irreversible, because there always exist irreversibilities in the real world. 3). In an actual electrical generating plant, the actual electricity generated is always less than the reversible electricity generation rate, which is higher and which represents an ideal or maximum. The difference between the ideal and actual electricity generation rates is directly related to the irreversibility of the process. 4). Similarly, for an electrical heat pump, the actual electricity required to operate the device is always greater than the reversible electricity input rate, which is lower and represents an ideal or minimum.

30) where ΣRt = Rt,t = 1∕HA and denotes the thermal resistance, while H denotes the overall heat transfer coefficient, which can be expressed as follows: H= 1 Rt,t A = 1 (1∕h1 + L1 ∕k1 + ..... , a pipe). 4 Fluid Mechanics A good grounding of fluid mechanics helps in understanding geothermal energy systems, as fluid flow problems often arise. Facets of fluid mechanics relevant to geothermal energy systems and their applications are introduced in this section to assist the reader. 1 Fluid Flow Fluid flow is the movement of a fluid.

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