EnergyPlus Simulation of Single-Coil Twin-Fan Air Conditioning System

Abstract

The goal of this thesis was to describe the development of a building energy simulation to show the potential energy performance of the newly-developed Single-Coil Twin-Fan (SCTF) air conditioning system. The objectives of this project were to develop a customized module of the energy efficient SCTF system, validate the model using industry-accepted simulation verification methods, and implement the module in a program with the capability to produce an energy simulation to show the potential performance of a typical building under a range of operating conditions and climates. Due to unique features such as a compartmented cooling coil and decoupled ventilation and recirculated air streams to the zone level, it is not possible to effectively simulate the SCTF system in any mainstream modeling application. A review of existing simulation software, computerized cooling coil models, and ventilation stream control was completed to establish the current state of the art. EnergyPlus was the simulation software chosen and two main modifications were made to the source code: decoupling of the ventilation air stream to the zone level and creation of a new dual duct terminal unit to control the separate air streams. An analytical and empirical verification of these modifications was completed using a three zone theoretical model as well as data from an installed system in the BCA Zero Energy Building (ZEB). It was found that the new terminal unit model performed as expected in the analytical model and was correlated with the empirical data from the ZEB. Comparison between simulated and measured air flow rates showed less than a 2% error for the time period selected, however, the overall shape of the two curves was dissimilar. This observation was attributed to the differences in the way the system was controlled in the simulation as compared to actual installed system. A conceptual development of the compartmented cooling coil was outlined and future effort in the modeling of the SCTF system was suggested including a more rigorous validation process and inclusion of reheat capabilities.