Development of stable calculation method for heat gain through walls | |
| Author | Bongkoj Sookananta |
| Call Number | AIT Thesis no. ET-02-1 |
| Subject(s) | Heat--Transmission Exterior walls--Thermal properties |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Masters of Engineering.School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. ET-02-1 |
| Abstract | A method for calculation of heat transfer through wall has long been of interest because it is a part of the method used to determine space cooling load, which is the rates at which heat must be removed from space to maintain a constant temperature. ASHRAE sponsored research projects in order to improve accuracy and stability of calculation and then published in its handbook. Response factor method has long been developed and recommended. This method is recursive as past calculated heat flux values are used to calculate a new value. One of subsequent development is conduction transfer function, which offer shorter calculation sequences and require smaller storage of past surface temperature and heat flux values. However, response factor and conduction transfer function methods give identical results. Inputs of these methods are surface temperature values, which for exterior temperatures, are obtained as sol-air temperatures and for interior temperatures, are assumed to be constant. The energy balance method has been developed in order to improve the vigor of the heat transfer calculation procedure. When this procedure is applied the new surface temperatures become additional unknowns. Consequently, the calculation is increasingly tended to diverge. The stability of recursive calculation of heat flux using response factors can be observed from the stability of the analogous dynamic system which from system theory, can be examined by considering the magnitudes of the eigenvalues of the state transition matrix. The system is said to be stable if and only if the magnitudes of the eigenvales of the state transition matrix are all smaller than one. Stability consideration is extended to see the variation of largest magnitude with sign of eigenvalues when time increment is changed for both single and multiple layers. The study developed a recursive calculation procedure, which has robust stability. The development is done in s-domain, in form of state equations. The heat fluxes and surface temperatures via a new procedure are close to those via EB: CTF and Finite difference methods. |
| Year | 2002 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Energy Technology (ET) |
| Chairperson(s) | Surapong Chirarattananon |
| Examination Committee(s) | Kumar, Sivanappan ;Singh, Sri Niwas ;Weerakorn Ongsakul |
| Scholarship Donor(s) | National Energy Policy Office and AIT partial scholarship |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2002 |