Abstract
The desirability of using a heat exchanger to improve the efficiency of gas-turbine plant of moderate gas temperatures and pressure-ratios has often to be considered in relation to the large space requirement and cost involved in the installation of a unit of the normal tubular type. This lecture shows that the possibilities of reducing the- bulk of the heat exchanger lie mainly in the use of passages of small diameter and length. The potentialities of the regenerative type of heat exchanger, and the requirements which have to be met if a practical unit working on this principle is to be achieved, are examined. It is thought that the most practical form of regenerator is one employing a rotating heat-exchanging element, and a stationary seal system to prevent the loss of high-pressure air; the relative merits of units of this type are discussed. The main problem to be overcome is that of developing an efficient and reliable sealing system. Work at the National Gas Turbine Establishment on a rotary-disk regenerator to study the sealing and general mechanical problems is described, together with the results of tests made on a smaller unit built to determine the heat-transfer properties of heat-exchanging elements of the flame-trap type.
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