The power loss factor β describes the loss of electrical power in CHP systems with a variable power-to-heat ratio when an increasing heat flow is extracted from the main

thermodynamic Thermodynamics is a branch of physics that deals with heat, work, and temperature, and their relation to energy, entropy, and the physical properties of matter and radiation. The behavior of these quantities is governed by the four laws of ther ...

electricity Electricity is the set of physical phenomena associated with the presence and motion of matter that has a property of electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described ...

generating process in order to provide useful

heat In thermodynamics, heat is defined as the form of energy crossing the boundary of a thermodynamic system by virtue of a temperature difference across the boundary. A thermodynamic system does not ''contain'' heat. Nevertheless, the term is al ...

. Usually, the power loss factor refers to extraction

steam turbine A steam turbine is a machine that extracts thermal energy from pressurized steam and uses it to do mechanical work on a rotating output shaft. Its modern manifestation was invented by Charles Parsons in 1884. Fabrication of a modern steam turbin ...

s in

thermal power station A thermal power station is a type of power station in which heat energy is converted to electrical energy. In a steam-generating cycle heat is used to boil water in a large pressure vessel to produce high-pressure steam, which drives a stea ...

s, which conduct a part of the steam in a heating condenser for the production of useful heat, instead of the low pressure part of the steam turbine where is could perform mechanical work. CHP principle and T-s-diagram

\beta = \frac

The picture on the right shows in the left part the principle of steam extraction. After the intermediate-pressure section of the turbine, i.e. before the low-pressure section, steam is diverted and flows into the heating condenser, where it transfers heat to the heating circuit (temperature level T_H about 100 °C) and liquefies. The remaining steam works in the low-pressure section of the turbine and is then liquefied in the condenser at approx. 30 °C. Then it is fed via the condensate pump to the feedwater circuit. The partial steam flow, which goes into the heating condenser at high temperature can no longer work in the low-pressure section and is responsible for the loss of power. The right-hand side of the picture shows the associated T-s diagram (see

Rankine cycle The Rankine cycle is an idealized thermodynamic cycle describing the process by which certain heat engines, such as steam turbines or reciprocating steam engines, allow mechanical work to be extracted from a fluid as it moves between a heat sourc ...

) for an operating state in which half of the waste heat is used for heating purposes. To the left of the red square, the white area below the red line corresponds to the waste heat (q_out), which is released via the condenser to the environment (ambient temperature level T_A). The entire red area corresponds to the useful heat (q_heat), the upper hatched part of this area corresponds to the power loss in the low pressure stage. Modern cogeneration plants have power loss ratios of about 1/5 to 1/9 when delivering heat in the range of 80 °C-120 °C.Danny Harvey
Clean building - contribution from cogeneration, trigeneration and district energy
Cogeneration and On-Site Power Production, september–october 2006, pp. 107-115 (Fig. 1) That means in exchange of one kWh of electrical energy ca. 5 up to 9 kWh of useful heat are obtained. Based on the

equivalence Equivalence or Equivalent may refer to: Arts and entertainment *Album-equivalent unit, a measurement unit in the music industry *Equivalence class (music) *''Equivalent VIII'', or ''The Bricks'', a minimalist sculpture by Carl Andre *'' Equival ...

of power loss and gain of heat, the power loss method assigns CO₂ emissions and primary energy from the fuel to the useful heat and the electrical energy.

References

{{Reflist Cogeneration Energy conversion