548 results about "Coefficient of performance" patented technology

Provided are: a working medium for heat cycles which has a low impact on global warming, a low temperature gradient, and a sufficiently low discharge temperature, and which exhibits excellent cycle performance (i.e. refrigeration capacity and coefficient of performance); a composition for heat-cycle systems; and a heat-cycle system. The working medium for heat cycles includes trifluoroethylene and 1, 2-difluoroethylene. Also provided are: a composition for heat-cycle systems; and a heat-cycle system which uses the working medium and the composition. It is prefereable that, in the working medium for heat cycles, the ratio of the total amount of trifluoroethylene and 1, 2-difluoroethylene be at least 20 mass%, and equal to or less than 100 mass%.

In devices used for the direct conversion of heat into electricity, or vice versa, known in the art as thermoelectric power generators, thermoelectric refrigerators and thermoelectric heat pumps, the efficiency of energy conversion and / or coefficient of performance have been considerably lower than those of conventional reciprocating or rotary, heat engines and / or vapor-compression systems, employing certain refrigerants. The energy conversion efficiency of power generating devices, for example, aside from the hot and cold junction temperatures, also depends on a parameter known in the art as the thermoelectric figure of merit Z=S2σ / k, where S is the thermoelectric power, σ is the electrical conductivity and k is the thermal conductivity, of the material that constitutes the p-type, and / or n-type, thermoelements, or branches, of the said devices. In order to achieve a considerable increase in the energy conversion efficiency, a thermoelectric figure of merit of the order of 10−2 K−1, or more, is needed. It is reasonably expected that such an order of magnitude, for the figure of merit, can be realized with a composition of matter, comprising magnesium, silicon, lead and barium, and optionally comprising one, or more, additional doping materials.

This invention provides heat engines based on various structures of internal combustion engines, such as a four-stroke piston-type combustion engine, two-stroke piston-type combustion engine, rotary combustion engine, or a free-piston type combustion engine. Said heat engine is provided with at least a heating chamber per piston or rotor, a heat exchanger unit disposed within said heating chamber through which thermal energy is extracted from a heat source and at least a port leading to a working chamber space from said heating chamber, and has a significantly increased heat transfer duration from the heat source to the working fluid within said heating chamber without increasing the number of strokes per power stroke in a cycle. Additionally, said heat engine is provided with an over expansion mechanism in conjunction with a compression means for intake charge. Thereby many of the operational characteristics of an Otto power cycle may be attained in said heat engine, and a heat source with a relatively low temperature may be accommodated through the combination of a lower compression ratio, the over expansion mechanism, and the boost of the intake charge.Another major objective of this invention is to provide a refrigerator based on the structures of the various heat engines disclosed in this invention and having a reversed operation of the heat engine. The invention combines the compression functionality of a compressor and the expansion functionality of a turbine in an air cycle machine into a single refrigerator unit having a simple mechanical structure, and provides a significantly increased heat removal rate or duration before the expansion stroke to reduce the temperature of the working fluid without increasing the number of strokes per discharge stroke of cooled working fluid in the cycle. Said refrigerator may include the over expansion mechanism or working fluid pressurization to increase the coefficient of performance and cooling load. In particular, said refrigerator uses a gas as the working fluid to avoid the negative impact of a conventional refrigerant on the environment.

Heat transfer compositions are usable in their own right or are suitable as a replacement for existing refrigeration usages. The compositions possess a reduced Greenhouse Warming Potential, yet have a capacity and energy efficiency (which may be conveniently expressed as the “Coefficient of Performance”) ideally within 20% of the values of those attained using R-134a, and preferably within 10% or less (e.g. about 5%) of these values.