Closed cycles power generation

Figure 5.2-9 The closed Brayton power generation cycle.

It is important first to distinguish between a closed cyclic power plant (or heat engine) and an open circuit power plant. In the former, fluid passes continuously round a closed circuit, through a thermodynamic cycle in which heat ((2b) is received from a source at a high temperature, heat (Qa) >s rejected to a sink at low temperature and work output (IT) is delivered, usually to drive an electric generator. 

The Joule-Brayton (JB) constant pressure closed cycle is the basis of the cyclic gas turbine power plant, with steady flow of air (or gas) through a compressor, heater, turbine, cooler within a closed circuit (Fig. 1.4). The turbine drives the compressor and a generator delivering the electrical power, heat is supplied at a constant pressure and is also rejected at constant pressure. The temperature-entropy diagram for this cycle is also... 

There are three potential types of OTEC power plants opcii-cyclc, closed-cycle, and hybrid systems. Open-cycle OTEC systems exploit the fact that water boils at temperatures below its normal boiling point when it is under lower than normal pressures. Open-cycle systems convert warm surface water into steam in a partial vacuum, and then use this steam to drive a large turbine connected to an electrical generator. Cold water piped up from deep below the oceans surface condenses the steam. Unlike the initial ocean water, the condensed steam is desalinated (free of salt) and may be collected and used for drinking or irrigation. 

Power generation plants such as the steam plant, the gas turbine plant, and combined cycle plants require the combustion of a fossil fuel. Now, combustion is a chemical reaction of fuel with an oxidant (usually oxygen), and it makes sense to examine the combustion process more closely and analyze its thermodynamic efficiency. This means that we will examine the furnace/combustor of Figures 9.8, 9.10, and 9.12. We will examine coal and gas combustion at the level needed for thermodynamic analysis, after discussing some commonly used coal combustion processes. 

For closed-cycle applications, such as for spacecraft, submarines, or transportation vehicles, the combinations of lightweight, reasonable power density, and compact size are favorable features in comparison with equivalent-capacity battery-based systems. In the International Space Station, for example, both electricity and water are provided by fuel cells. Fuel cells have not only been used in space exploration, but also in submarines (because they generate no noise or vibration). They have also been used to recover the energy from methane that is generated by wastewater, by garbage dumps, and more recently in automobiles as an alternative to the IC engine. 

The problem of NP fuel supplying could be solved by FR operating in closed nuclear fuel cycle (NFC) and enabling to involve effectively uranium-238 into power generation. 

An OTEC installation comprises a power generating subsystem subsystems to convert the electric powerproduced to forms useful for power transmission and fuel production energy storage and transfer equipment equipment for position control of floating systems and facilities (ships, platforms, or on-land installations) to house and maintain the total system. Closed-cycle OTEC systems are suitable for installation on ships and, therefore, offer a potential way for OTEC plantships to draw power from the entire area of the tropical oceans and provide a major new source for renewable fuels production. 

Desirable characteristics of working fluids for closed-cycle OTEC include vapor pressme between 700 and 1400 kPa (100-200 psi) at 25°C, low volmne flows of vapor per kilowatt of generated power, and high heat-transfer coefiicient for the liquid films on the HX siufaces. The... 

Now, power generation plant named GT-MHR which consists of 600MWth HTGR connected with Power Conversion Module (closed cycle regenerative gas turbine system contained within a single vessel) is under development by the US. and Russian cooperation. 

Beginning in 1960 the municipal energy utility of Oberhausen (EVO) operated on its grid a closed-cycle, hot-air turbine plant for the combined generation of electricity and district heat. Due to increasing demand, an extension of the power plant capacity was decided upon in 1971. 

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