First Order Multivariate Markov Chain Model for Generating Synthetic Series of Weather Data to Evaluate the Performance of Open Cycle Solar Desiccant AirConditioning System

摘要

Dehumidification of air conditioning is traditionally accomplished with vapour refrigeration equipment. The disadvantage of this air handling process is that the temperature of the air must be cooled below its dew-point which is deemed to be energy expensive. An open cycle liquid desiccant dehumidification system driven by solar energy was emerged as a potential alternative to conventional vapour refrigeration system for humidity control in air conditioning. This system can utilize solar energy and can possibly provide cooling more efficiently. As it is an open cycle system, the performance of the proposed system is more sensitive to the ambient conditions. Unlike other types of solar utilization methods which solar radiation is the only dominate weather parameter, the performance of the open cycle solar desiccant dehumidification system is also related to the ambient humidity and temperature significantly. For continuous operation, storage system and auxiliary heat source should be considered in the system in case solar radiation is not available. Thus, sizing represents an important part of the solar desiccant dehumidification system design. Firstly, this paper presents a stochastic simulation approach to syntactical generate a series of meteorological parameters using 15 years of real weather conditions of Hong Kong (between 1979～1988 and 1996～2000). Specifically, a first-order multivariate Markov chains model is developed to represent ambient temperature, humidity and isolation. The static properties of real weather data, like mean value, standard variance and persistence of certain climate, are well preserved in the syntactically generated weather data. Further more, the inter-dependence of the solar radiation, ambient temperature and humidity are well reflected. The information provide by this series of meteorological parameters is quite useful to the sizing of the solar C/R, storage capacity and capacity of auxiliary heat source. Secondly, using the synthetic series of weather condition developed in this study, the performance of the open cycle liquid desiccant dehumidification system was simulated. The results reveal that the open cycle desiccant system can meet most of the latent load through out the cooling season if the components are proper sized and the energy saving.