By ventilating the vehicle’s interior during a soak, the peak cooling load is reduced and therefore the air-conditioning needs less power. This in turn translates to a smaller air-conditioning unit which would consume less power, be lighter and more compact. This solar driven ventilation of the vehicle’s interior during a soak is defined as precooling. During this project the best precooling strategy for passenger vehicles was found by investigating and testing different precooling strategies and evaluating them according to their thermodynamic performance, their potential implementation and their influence on the required cooling performance of the airconditioning cycle. The best performances were achieved by strategies with a high air flow rate and a relatively low air inlet temperature. Two categories of precooling strategies were examined: natural convection and forced convection strategies. Openings in the vehicle’s body that fit to all strategies had to be found; with a big potential concerning their thermodynamic performance and other aspects like prevention against water penetration. The best investigated precooling strategies proved to be the one which used the design outlet as an inlet and the opening of the HVAC as an outlet. With these openings a good air flow through the whole cabin can be guaranteed. In addition to that the strategy only uses existing openings of the body which prevent against water penetration. The required installation space for this strategy already exists and can be considered for the package of next generation vehicles.

Thesis (M. Eng. Sc.)--University of Adelaide, 1984. / Includes bibliographical references (leaves [104-105]).

Thesis (Ph. D.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 121-126). Also available in print.

Thesis (Ph. D.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 121-126). Also available online.

This study concerns an investigation into air movement and associated energy flows within the environment of a synthetic fibre producing factory. A multiplicity of airconditioning and ventilation systems were operated within the factory to provide a suitable atmosphere for the yarn, and also to allow some degree of comfort in hot production areas. Potential for improved operation of these systems was anticipated. Initial experiments showed certain anomalies and problems relating to air conditions and air movement; and an important facet of the production areas was identified as the regular partitioning created by the machine layout. A review of previous studies of building air flows indicated a lack of information relating to industrial and partitioned areas. Mathematical relationships for air flows were studied and the interactions of similar, closely spaced partitions were considered. A series of model scale tests using simple layouts supported a theory of interaction. The effect was substantial for wall type partitions and a considerable overestimation could result from the simple additive approach to determination of total resistance. At the factory a computer based monitoring scheme was designed and installed in order to establish environmental conditions and energy flows. The concept of "total thermal efficiency" was developed as a means of evaluating the performance of some of the air-conditioning systems. Considerable variations were evident between seasons and between systems; improvements being possible and recommended. Air flows were also investigated using Nitrous Oxide as a tracer gas. The effect of the internal partitioning combined with the high degree of ventilation and air-conditioning was to "compartmentalize" the spaces between the machines in the production areas, semi-isolating each from its neighbours. Thus, the results of the simplified model scale work could not be applied directly. However the isolation of the spaces offers potential for better systems operation by reducing air-conditioning requirements.

No description available.

The heating and cooling requirements after a shutdown period of the heating ventilating and air conditioning (HVAC) systems in buildings are studied through an analytical model. The parameters affecting the preconditioning and storage loads which are of particular importance are identified. A mathematical computer model is developed to facilitate the analysis of the shutdown loads. Zones are grouped in terms of heavy, medium and light weight construction for the study. For a specified zone, the ratio of the inside surface area to the outside exposed area, A(s)/A(w), is an important parameter in predicting the additional loads resulting from system shutdown. The computer model is validated with known computer programs, namely DOE-2, BLAST, and DARE-P. A simplification to the model is proved to be adequate for the study. The zones with similar weight characteristics and the same A(s)/A(w) ratio, prove to have the same temperature profiles during the shutdown period, provided that they are at the same ambient conditions. Design guidance and procedures for predicting the preconditioning and storage loads using the models are developed. In addition, the use of DOE-2 and ASHRAE weighting factor method for shutdown load predictions is demonstrated for generic and custom applications.

No description available.

No description available.

M.Ing. / In this study, alternative heat pump systems are compared for use in South African climatic conditions. Monthly heating/cooling capacities and coefficients of performance for air, vertical and several horizontal ground-source systems are calculated for Pretoria and Johannesburg. The desired type of heat exchanger is determined by considering economic factors such as the total costs, comprised of the capital and operating costs. The cost-effectiveness on investments of each system is calculated, with parameters such as the payback period, net present value and internal rate of return ...