مقاله انگلیسی رایگان در مورد شبیه سازی یک سیستم خنک کننده هوای غالب منفعل – IEEE 2018

In modern days, climate control has become an everyday challenge. Due to global warming, indoor temperatures of residential homes can rise to uncomfortable levels, especially in summer months. By making use of low exergy systems for heating and cooling of residential homes thermal comfort can be improved and energy efficiency can be increased [1]. Through air conditioning, indoor temperatures can be regulated to comfortable levels, despite ambient conditions. However, taking electricity prices and environmental factors, i.e. the supply of energy through coal based electricity plants in consideration; the use of air conditioning should be limited. Above one third of the world’s primary energy demand is due heating and cooling appliances, which include air conditioning [2]. Power generation in South Africa is predominantly dependant on fossil fuels. Fossil fuelled power generation is not only limited in available resources, but possess a negative effect on the environment that include the assistance of global warming. In order to possibly ensure a safe future energy demand it is imperative to investigate and implement the use renewable energy. It is, therefore, of utmost importance to investigate alternative cooling methods that can be implemented, either assisting or in some instances the replacement of traditional air conditioning systems. Two typical types of cooling mechanisms can be considered for residential air cooling; passive – and active systems. A passive system is defined as a building envelope that uses environmental potentials such as wind or solar energy. Active systems involve various mechanical and electric components, such as fans and heat pumps. The proposed solution for this paper is a passive, supported by an active system. This paper proposes a solution where ambient air is cooled through an earth to air heat exchanger. Air is forced, by means of a fan, into a piping system which is buried underground. This air is then cooled through a heat exchanger, where the outlet is connected to a room. Allowing cooler ‘ambient’ air to enter a room will result in less electricity needed by an air conditioning system to obtain the required temperature. This paper, furthermore, proposes two simulation models. The first model is to simulate the air cooling through the heat exchanger, for design purposes. The second model simulates the transient cooling of a room, open to the environment, receiving an air flow. By utilising this second model, a room’s cool-down rate and duration can be simulated. These simulation results, in conjunction with the first proposed model, can then be used to size the heat exchanging system. In the following section a literature survey is provided, followed by the proposed simulation models. A result section is given in Section 4 where experimental data from a test bench is used to verify the proposed models. A case study follows in Section 5.