MHD Generator Using an Emulsion

The authors propose an MHD generator in which the, working fluid is an emulsion consisting of gas or steam in a liquid metal; the emulsion is subjected to a magnetic field and expanded in the MHD channel itself. Various solutions involving liquid metals have been proposed, but the transfer of energy from the gas to the liquid metal is usually inefficient. Moreover, there are considerable losses as the liquid metal enters and leaves the magnetic field. With the solution proposed by the authors, however, if the emulsion is sufficiently fine and homogeneous, the problem of energy transfer between the non-conducting, but elastic, gas or steam and the non-elastic, but conducting, liquid metal is solved in a highly satisfactory manner. Moreover, it is then possible to locate MHD loops entirely within the magnetic field, so that the gas is introduced and extracted while the liquid metal circulates in a closed circuit. In this way MHD losses as the liquid metal enters and leaves the magnetic field are eliminated. With MHD loops of this type the working fluid can be made to flow in complete thermodynamic cycles; compression of the gas (at low temperature) may also be achieved within an MHD system using an emulsion, so that the assembly is completely closed and without moving parts. The authors describe various arrangemements by means of which suitable thermodynamic cycles can be achieved, allowance being made for the limitations imposed by the nature of the working fluid (possible expansion ratios in the case of an emulsion) and for partial evaporation of the liquid metal. A number of loops are arranged in series on the gas flow, each operating at a successively lower temperature, this being achieved by adventitious recycling of the liquid metal. The authors also describe the way in which such an assembly of loops can be linked to a complete cycle comprising a heat exchanger and, possibly, a conventional steam cycle. The authors conclude by stating the possible thermal efficiency of such assemblies in the following two cases: an autonomous MHD generator into which the MHD working fluid passes at a temperature as low as ambient; an MHD generator coupled to a conventional steam-turbine power station. (author)