Development aspects of a high temperature heat pipe heat exchanger for high temperature gas-cooled nuclear reactor systems

[摘要] ENGLISH ABSTRACT: High temperature heat sources are becoming an ever-increasing imperative in theprocess industry for the production of plastics, ammonia and fertilisers, hydrogen, coal-toliquidfuel and process heat. Currently, high temperature reactor (HTR) technology iscapable of producing helium temperatures in excess of 950°C; however, at thesetemperatures, tritium, which is a radioactive contaminant found in the helium coolantstream, is able to diffuse though the steel retaining wall of the helium-to-steam heatexchanger. To circumvent this radioactivity problem, regulations require an intermediateheat exchange loop between the helium and the process heat streams. In this paper, theuse of a uniquely designed sodium-charged heat pipe heat exchanger is considered, andhas the distinct advantage of having almost zero exergy loss as it eliminates theintermediate heat exchange circuit.In order to investigate this novel heat pipe heat exchanger concept, a specialintermediate-temperature (± 240°C) experimental heat pipe heat exchanger (HPHE) wasdesigned. This experimental HPHE uses Dowtherm A as working fluid and has two glasswindows to enable visual observation of the boiling and condensation two-phase flowprocesses. A high temperature air-burner supply simulates the high temperature stream,and the cold stream is provided by water from a constant-heat supply tank. Thisexperimental apparatus can be used to evaluate the validity of steady-state and start-uptransient theoretical models that have been developed.This paper will highlight the special design aspects of this HPHE, the theoretical modeland the solution algorithm described. Experimental results will be compared with thetheoretically calculated results. The theoretical model will then be used to predict theperformance of a high temperature (sodium working fluid at 850°C) HPHE will beundertaken and conclusions and recommendation made.

[发布机构] Stellenbosch University