This study investigated different underground bulk air heat exchanger (>100 m3/s) design criteria. It was found that no single document exist covering these heat exchangers and therefore the need was identified to generate a guideline with decision analyser steps to arrive at a technical specification. The study investigated the factors influencing the heat exchanger designs (spray chambers, towers and indirect-contact heat exchangers) and the technical requirements for each. The decision analysers can be used to generate optimised user-friendly fit-for-purpose bulk air heat exchanger (air cooler and heat rejection) designs. The study was tested against a constructed air cooler and heat rejection unit at a copper mine. It was concluded that the decision analysers were used successfully. It is recommended design engineers use these decision analysers to effectively design other heat exchangers. / Dissertation (MEng)--University of Pretoria, 2013. / gm2014 / Mining Engineering / unrestricted