Rising energy prices have contributed to the development of heat pump-based heating systems in Sweden. Low flow temperature in the secondary heat distribution system to rooms is a requirement for energy-efficient systems. This increases the thermal efficiency of the heat pump and decreases thermal losses in the distribution system. Flow temperatures in water-based systems for heat distribution in buildings have been decreased from 55C to temperatures around 30C. This is to maximize the efficiency of heating systems that are based on heat pump technology.
This research was to assess the performance of air infiltration, the corresponding energy consumption, indoor contaminant level for residential buildings in Harbin, a typical city in the severe cold region of China. Based on questionnaire survey and field measurements, the prototypical apartment building includes its physical structure, air leakage and life style of occupants has been determined. Then unsteady-state numerical simulations were carried out by the use of COMIS.
Multiple regression analysis is used to predict the mean room velocity and determine the most influencing parameters on the velocity. More than 120 experiments for four different heat source locations were carried out in a test chamber with high level mixing ventilation. The measured parameters, such as supply air momentum, room heat load, Archimedes number and local temperature ratio, were used as independent variables. These parameters are examined by two methods: a simple regression analysis incorporated into scatter matrix plots; and multiple stepwise regression analysis.
We conducted an on-site test of air-conditioning systems in a hotel in Changsha, Hunan, China in the summer of 2003. And indoor particulate matters, bioaerosols were the main pollutants sampled from indoor spaces and three air-conditioning systems, one of which serves the lobby of the hotel, with the other two supply fresh air to the cook room and dinning-rooms. Short-term and long-term sampling of deposited particles in the air-conditioning systems was carried out and their size distribution was tested by Optical Particle Counters (OPCs).
We describe the flow in an underfloor plenum. We show that the geometry of the plenum causes the flow to exhibit two-dimensional dynamics and to develop flow patterns that are determined by the inlets of the underfloor into the plenum void. We describe laboratory experiments that simulate these flows and also show that the location and number of diffusers in the plenum has little effect on the underfloor flow. Depending on the location of the inlets to the plenum, the flow can exhibit complex vortex patterns and may be time dependent.
Floor-supply air-conditioning system with Coanda effect is introduced to a theater hall. This system supplies air from floor diffusers set beneath the seat backrest in front of occupants. Supplied air moves upward along the backrest board inducing the circumambient air resulted in airflow temperature difference reduction. Thermal environment was measured under various heat load conditions in the theater hall. Supply air flow along and radiation effect from the seat backrest in front were confirmed using the floor-supply system.
A comprehensive modelling of a compact double skin facade equipped with a venetian blind is proposed here. The modelling is done using CFD approach to asses the air movement inside the ventilated facade channel and appropriate radiation model for long and short wave exchanges. The impact of solar radiation on temperature and velocity fields as a function of some parameters such as beam radiation incidence angle, blade angle of solar protection, etc. is analysed.
From the beginning of 2006 all new buildings (residential, commercial, industrial etc.) must have an energy declaration based on the calculated energy performance of the building, including HVAC and lighting systems. This energy declaration must refer to the primary energy or CO2 emissions. The directive also states that the energy performance calculation must take into account the indoor climate, but gives no guidelines.
The problem of achieving good air quality in dwellings whilst saving energy has led to a number of solutions many involving the use of fan power. This paper describes a programme of testing, that has continued over the last three years, of a passive low energy ventilation system. The systems components are supply air window in combination with passive stack vents. Installations have been monitored in unoccupied dwellings in Poland, Denmark and Ireland and user feedback is now being collected, the units now being occupied.
A modified k-e model that restricts turbulent time scale using Durbin’s limiter was applied for numerical prediction of wind pressure distributions of building models. It is known that the standard k-e model tends to overestimate wind pressure of windward
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