Browsing by Author "Dobson, Robert T."
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- ItemHeat pipe heat exchanger for high temperature nuclear reactor technology(Global Digital Central, 2013) Dobson, Robert T.; Laubscher, RynoENGLISH ABSTRACT: When a high temperature nuclear reactor is used to supply process heat, nuclear regulators require an intermediate heat transfer loop between the primary reactor coolant stream and the secondary process heat stream. A sodium-charged heat pipe heat exchanger design is presented that circumvents the need for an intermediate coolant loop. This is done by physically separating the reactor coolant and secondary coolant by two pipe walls, and a vapour section and a liquid section. This tritium diffusion resistant design for the re-heater, preheater, steam generator and super-heater heat supply system of a 232 MW-electrical pebble bed modular reactor heat source for a superheated Rankine power cycle is presented. A theoretical model was then used to produce preliminary design sizes (tube sizes, tube lengths, working fluid, etc.) for a sodium-charged heat exchanger to be used with a high temperature gas-cooled reactor.
- ItemA novel indirect parabolic solar cooker(David Publishing, 2017) Craig, Omotoyosi O.; Dobson, Robert T.; Van Niekerk, WikusThe continuous increase in global demand and cost of electricity are some of the reasons that solar cooking has received much attention recently. Another factor which has also contributed to the acceptance of solar cookers is global campaigns against actions that contribute to climate change. Various types of solar cookers are currently in existence, these are box, panel and parabolic cookers. Some solar cookers only function when the cooking section is placed under direct sunshine, while others have been modified to cook without directly exposing their cooking section to the sun. Most solar cookers face similar challenges, and these include, exposure of users to sun, inability to function at night or when there is no sunshine, low utilization efficiency and technical complexities. This report presents an indirect parabolic cooker that eliminates the identified solar cooker challenges. The cooker uses a parabolic reflector to focus the sun rays to a frustum shaped receiver that was placed at its focus. The cooker has an insulated cooking/heat storage tank which was separated from the dish and cavity receiver system. The heat transfer fluid was distributed through the system with the aid of high temperature flexible hoses. Several cooking tests including water boiling and pancake baking were done, an extensive analysis of cooking based on the international testing procedures for solar cookers was also carried out. This solar cooker had a utilization efficiency of 39%, an overall calculated exergy efficiency of 0.05% and an average characteristic boiling time of approximately 13 minutes/kg. The manufactured solar cooker in this study was used for family cooking.