Method for achieving hydraulic balance in typical Chinese building heating systems by managing differential pressure and flow

Hydraulic unbalance is a common problem in Chinese district heating (DH) systems. Hydraulic unbalance has resulted in poor flow distribution among heating branches and overheating of apartments. Studies show that nearly 30% of the total heat supply is being wasted in Chinese DH systems due to a lack of pressure and flow control. This study investigated using pre-set radiator valves combined with differential pressure (DP) controllers to achieve hydraulic balance in building distribution systems, and consequently save energy and reduce the emissions. We considered a multi-storey building modelled in the IDA-ICE software, along with a self-developed mathematical hydraulic model to simulate its heat performance and hydraulic performance with various control scenarios. In contrast to the situation with no pressure or flow control, this solution achieves the required flow distribution and close-to-design room temperatures, as well as 16% heat savings, 74% pump electricity savings, and proper cooling of supply water. The energy consumption savings would therefore have positive environmental impacts, and be reflected in seasonal reductions of 2.1 kg/m² CO₂, 0.02 kg/m² SO₂, and 0.01 kg/m² NO_x for 3rd step energy efficiency buildings in Beijing.     

Morphology of TiN thin films grown on SiO2 by reactive high power impulse magnetron sputtering

Thin TiN films were grown on SiO₂ by reactive high power impulse magnetron sputtering (HiPIMS) at a range of temperatures from 45 to 600 °C. The film properties were compared to films grown by conventional dc magnetron sputtering (dcMS) at similar conditions. Structural characterization was carried out using X-ray diffraction and reflection methods. The HiPIMS process produces denser films at lower growth temperature than does dcMS. Furthermore, the surface is much smoother for films grown by the HiPIMS process. The [200] grain size increases monotonically with increased growth temperature, whereas the size of the [111] oriented grains decreases to a minimum for a growth temperature of 400 °C after which it starts to increase with growth temperature. The [200] crystallites are smaller than the [111] crystallites for all growth temperatures. The grain sizes of both orientations are smaller in HiPIMS grown films than in dcMS grown films.     

The Effects of Water Soluble Arabinoxylan on Gelatinization and Retrogradation of Starch

The effects of soluble pentosans, in the form of the main water-soluble arabinoxylan from rye grain, on the gelatinization and retrogradation of starch were studied. Five different starches, waxy, amylomaize, wheat, maize and potato starches and wheat flour were used. The water contents of the samples varied from 46.5 to 50%. Differential scanning calorimetry (DSC) showed that the arabinoxylan had a negligible effect on the gelatinization. However, the arabinoxylan did affect the retrogradation. The recrystallization process is particularly sensitive to the water content in the sample. The maximum extent of recrystallization occurs when the starch concentration is between 50 and 60%. The effects of the arabinoxylan are probably caused by the water absorption ability of the arabinoxylan. i.e. control of the water availability of the starch which thereby, increases the retrogradation. The effects of arabinoxylan addition are. however, dependent on the initial starch concentration. The results of the rheological measurements agreed with the DSC measurements because potato starch gels (42.–42.8% on dry matter basis (d.b.)), with added (2% d.b.) arabinoxylan, were more rigid after seven days of storage than pure potato starch gels.