Operation Thermal compressors

The Vuilleumier refrigeration cycle has frequently been described as a Stirling cycle with a thermal compressor instead of a mechanical compressor. Recently, it has generated much interest in the area of spacecraft applications where the advantages of long-lifetime operation, low acoustical noise, and minimal wear of moving parts have been extensively examined. 

For air compressors Operating safety Thermal stability, Volatility Resistance to oxidation Extreme pressure and anti-wear (compressors) properties Low coking tendency (hot reciprocating compressors)... 

Mechanical Expanders Reciprocating expanders are very similar in concept and design to reciprocating compressors. Generally these units are used with inlet pressures of 4 to 20 MPa. These machines operate at speeds up to 500 rpm. The thermal efficiencies (actual enthalpy difference/maximum possible enthalpy difference) range from about 75 percent for small units to 85 percent for large machines. 

The operation of a motor at a rated load may be for an unlimited period to reach thermal equilibrium (Figure 3.1) and possible applictilions are pumps, blowers, fans and compressors. 

Most ethylene plants operate continuously with the expanders operating at or near design conditions. If necessary, due to their unique design characteristics, radial inflow turboexpanders can accommodate a wide range of process conditions without significant losses in thermal or mechanical efficiency. Expanders may be loaded with booster compressors, gear-coupled generators, dynamometers, or other in-plant mechanical equipment such as pumps. In ethylene plants, turboexpanders are typically used in eitlier post-boost or pre-boost applications. 

Reduction of the catalyst/hydrocarbon time in the riser, coupled with the elimination of post-riser cracking, reduces the saturation of the already produced olefins and allows the refiner to increase the reaction severity. The actions enhance the olefin yields and still operate within the wet gas compressor constraints. Elimination of post-riser residence time (direct connection of the reactor cyclones to the riser) or reducing the temperature in the dilute phase virtually eliminates undesired thermal and nonselective cracking. This reduces dry gas and diolefin yields. 

The efficiency of this preprototype device was low due principally to the thermal mass of the copper buss bars, convection losses associated with the air cooled design and radiation losses at the high operating temperatures. Current work is directed at staged compressors (more than one alloy) operating over smaller temperature ranges supplied by a liquid heat transfer media. 

Catalytic combustion for gas turbines has received much attention in recent years in view of its unique capability of simultaneous control of NOX) CO, and unbumed hydrocarbon emissions.1 One of the major challenges to be faced in the development of industrial devices is associated with the severe requirements on catalytic materials posed by extreme operating conditions of gas turbine combustors. The catalytic combustor has to ignite the mixture of fuel (typically natural gas) and air at low temperature, preferably at the compressor outlet temperature (about 350 °C), guarantee complete combustion in few milliseconds, and withstand strong thermal stresses arising from long-term operation at temperatures above 1000°C and rapid temperature transients. 

The most difficult task for the safety-valve sizing is the achievement of the maximum flow-rate to be discharged. In case the safety valve is used to save the operation of a pump or compressor, their maximum mass-flow-rate is the basis for the sizing. Much more effort is necessary in systems where vessels, complex piping systems, pumps, and thermal expansion can activate the safety valve. In most cases, some discussions with the relevant authorities are necessary to clarify all assumptions for risks relevant to safety. 

The denominator in this efficiency definition quantifies all of the net thermal energy that is consumed in the process, either directly or indirectly. For a thermochemical process, the majority of the high-temperature heat from the reactor is supplied directly to the process as heat. For HTE, the majority of the high-temperature heat is supplied directly to the power cycle and indirectly to the HTE process as electrical work. Therefore, the summation in the denominator of Eq. (1) includes the direct nuclear process heat as well as the thermal equivalent of any electrically driven components such as pumps, compressors, HTE units, etc. The thermal equivalent of any electrical power consumed in the process is the power divided by the thermal efficiency of the power cycle. For an electrolysis process, the summation in the denominator of Eq. (1) includes the thermal equivalent of the primary electrical energy input to the electrolyser and the secondary contributions from smaller components such as pumps and compressors. In additional, any direct thermal inputs are also included. Direct thermal inputs include any net (not recuperated) heat required to heat the process streams up to the electrolyser operating temperature and any direct heating of the electrolyser itself required for isothermal operation. 

Because at the RSR level the separators are not yet known, the cost of recycles may account only for transport and conditioning of streams. Transporting gases involves high capital and operation costs for compressors. Similarly, thermal feed conditioning may involve expensive equipment, such as evaporators and furnaces, as well as the cost of heat carriers. 

If the compressor and turbine operate adiabatically but irreversibly with efficiencies % = 0.83 and 17, = 0.86, what is the thermal efficiency of the power plant for the given conditions ... 

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