HVAC System Simulation And Analysis Based On Uncertain Inner Heat Gains

Through analyzing practical problems in HVAC system operation, this paper points out that it is necessary to use full-condition simulation and analysis to verify the HVAC design in the preliminary design stage, and it is useful to estimate quantificationally the possible problems in the system's future operation. For large scale commercial buildings, inner heat gains are the most important factor that affects the building thermal environment. Since the inner heat gains acts in a uncertain way in time serial and space, the uncertain property of the inner heat gains is the main reason to result in the problem of inhomogeneous temperature distribution in the HVAC system operation.Presently, fixed schedule is generally used to describe the inner heat gains in the state of arts HVAC system simulation. However, this description couldn't reflect the uncertain characteristic of inner heat gains, therefore the simulation couldn't accurately estimate the possible conditions which may happen in the real system operation, and even worse, it may result in the designer's error decisions. In order to make the simulation more close to the real condition, it is required to use a range rather than just a certain point as the simulation input of the inner heat gains. In this way, the simulation would conduct not only the comprehensive verification of climate but also the comprehensive analysis of inner heat gains, so as to completely check out the possible problems in real system operation, and to achieve the optimization and improvement of design.To solve the above problems, this paper presents a new mathematic methodology to deal with the region operation, which including the definition, the operation rules, and the theoretical proving of region operation. This new mathematic methodology could be used to calculate the results under the interaction between uncertain factors and controlling means. This paper also presents the process and applications of region operation through some case study.By applying this region operation methodology into HVAC system simulation analysis, this paper presents a new HVAC system simulation method under uncertain inner heat gains. In order to testify the validity of this method, this paper provides a series of comparison and analysis between new method and Monte Carlo method.With the applications of the HVAC system simulation method under uncertain heat gains, and also the comparison with the one schedule method, it shows the advantage of this new method.