English

A control scheme for an air conditioning system is proposed, based on the continuous monitoring of the thermal, electric and climate variables. The dynamic behavior of the relevant variables is determined and expressed in terms of a compact model (the system transfer function). In this study, the indoor temperature control loop has been implemented using a conventional PI algorithm. The controller varies the speed of the compressor motor by means of a frequency inverter, which, in its turn, controls the refrigeration load.

In this paper, three-dimensional air flow distributions in a typical island platform under both natural and mechanical ventilation operation modes were simulated for the whole process of the train entering, staying in and departing from the platform. The mechanical ventilation modes include over-platform supply/under-platform exhaust (OSUE) and overplatform supply/over- platform exhaust (OSOE). Based on the data obtained from the simulations, the effects of natural and mechanical ventilation system on platform air distribution were analyzed.

The indoor climate system, which serves a building with a proper indoor air quality and thermal comfort, has been predominantly designed based on the initial cost. A life cycle approach could improve both the economic and environmental performance. For example, the energy use could decrease. There has been a lack of knowledge, models and simulation tools for determining the life cycle cost (LCC) for an indoor climate system. The objective of this paper is to present a model for calculating the LCC for indoor climate systems. Focus is on indoor climate systems for premises and dwellings.

District Energy Systems (DES), e.g. District Cooling Systems (DCS) and District Heating Systems (DHS), have been widely applied in large institutions in the United States, such as universities, government facilities, commercial districts, airports etc. The hydraulic system of a large DES can be very complicated. They often stem from an original design that has had extensive additions and deletions over time. Expanding or retrofitting such a system involves large capital investment. Consideration of future expansion is often required.

Cyclone purifier has been conventionally used for separating particles from exhaustion. This paper, however, tried to develop a cyclone purifier for fresh air treatment in ventilation. Simulations were carried out based on continuity equation, momentum equation, RNG k-epsilon turbulent flow equation and Discrete Phase Model; the discrete griddings were both structural and non-structural; the software used was FLUENT. The separation efficiencies, pressure drops and the flow patterns of air in the cyclone purifier were simulated.

According to the cold climate in winter, a new novel ventilation system was put forward based on the analysis of the heat distribution at the subway station in Harbin. There was no special heating system in winter for subway station with such a ventilation system. In this paper, three dimensional model of the subway station was built, a mathematical model of the novel ventilation system was developed based on the k-ε standard turbulence model, and computational fluid dynamics (CFD) simulations for the ventilation system were performed to clarify the conditions of the temperature fields.

As a comfortable and energy-efficient air conditioning system, the application of radiant floor heating system is increasing greatly used in the north of China. Now, more and more people begin to be aware of the problem of thermal comfort degree in radiant floor cooling room. This study aims at developing a radiant floor cooling system using the existing radiant floor heating system. Unlike an all-air cooling system, the radiant floor cooling system could remove the cooling by convection and radiation.

Urban issues to be resolved concerning building energy systems involve not only global warming but also the heat island phenomenon, the planning of urban infrastructures for electricity generation and distribution, and water purification.

A mathematical model has been developed for simulating the performance of small-scale fuel-cell cogeneration systems. An experimental programme has been conducted to calibrate the model (i.e. establish its inputs) to simulate the performance of a prototype solid-oxide fuel-cell system. Data from a disjunct set of experiments were used to empirically validate this model and its calibration.

The systematic numerical simulation program is developed to calculate the total energy efficiency of housing polymer electrolyte fuel cell co-generation system (PEFC-CGS) which is combined with hot water floor heating (HWFH). This simulation program can also predict actual building physics of heat transfer such as mutual radiant heat among interior surfaces and thermal strage relating with piping pitch of hot water and so on. The indoor temperature can be controlled by PMV (Predicted Mean Vote) to take account of thermal sensing affected radiant heat.