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A new sort of nanofluids phase change materials (PCMs) is developed by suspending small amount of TiO 2 nanoparticles in saturated BaCl 2 aqueous solution. The resulting nanofluids PCMs possess remarkably high thermal conductivities compared to the base material. Cool storage/supply experiments conducted in a small apparatus have shown the excellent phase change performance of the nanofluids PCMs. The cool storage/supply rate and the cool storage/supply capacity all increase greatly those that of BaCl 2 aqueous solution without added nanoparticles. The higher thermal performances of nanofluids PCMs indicate that they have a potential for substituting conventional PCMs in cool storage applications.

Lyocell fibers were produced from a cheap pulp with a high hemicellulose content and from a conventional pulp with a high a-cellulose content. The mechanical properties, supermolecular structure, fibrillation resistance, and dyeing properties as well as the fibril aggregation size of the high hemicellulose Lyocell fiber and high a-cellulose Lyocell fiber were compared. The results showed that the high hemicellulose spinning solution could be processed at a higher concentration, which improved the mechanical properties and the efficiency of the fiber process. Compared with the high a-cellulose Lyocell fiber, the high hemicellulose Lyocell fiber had better fibrillation resistance and dyeing properties. Therefore, it is feasible that this cheap pulp with a high hemicellulose content can be used as a raw material for producing Lyocell fibers.

In the present paper the difference in the structure and properties of Lyocell fibers with different hemicelluloses content was investigated. The supermolecular structure and the morphological characterization were compared. The fibril aggregation size was estimated by the crosspolarization magic-angle spinning carbon-13 nuclear magnetic resonance (CP/MAS 13 C-NMR) spectroscopy. Meanwhile, the difference in the mechanical, the fibrillation resistance and the dyeing properties of Lyocell fiber with different hemicelluloses content was also ana-

Prediction of MW scale and MWD of cellulose by means of a rheology‐based method is developed. In this method, for the cellulose/NMMO·H2O solution, it is assumed that the cellulose MW values calculated by the Rouse terminal relaxation time can be regarded as the peak MW on the MWD curves of cellulose. Consequently, it is realized that the reciprocal of the frequency is converted to the MW scale, obtaining MWD scale curves of cellulose. Meanwhile, the obtained results are compared with those measured by the GPC method. The comparison shows that the calculated peak MW values are approximately equal, the calculated PDI values and MWD curves have the same trends. Consequently, it may be feasible to compare the MW scale and MWD of cellulose by using the rheology‐based method. In addition, the rheology‐based method is simple and fast. Therefore, it is a useful and easy way to analyze the MW scale and MWD of cellulose in the fiber industry. POLYM. ENG. SCI., 48:102–106, 2008. © 2007 Society of Plastics Engineers

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Due to the surface water in the upper reaches of Yangtze River in China containing large amounts of silt and algae, high content of microorganisms and suspended solids, the water in Yangtze River cannot be used for cooling a heat pump directly. In this paper, the possibility of using Yangtze River, which goes through Chongqing, a city in southwest China, as a heat source-sink was investigated. Water temperature and quality of the Yangtze River in the Chongqing area were analyzed and the performance of water source heat pump units in different sediment concentrations, turbidity and algae material conditions were tested experimentally, and the water quality standards, in particular surface water conditions, in the Yangtze River region that adapt to energy-efficient heat pumps were also proposed. The experimental results show that the coefficient of performance heat pump falls by 3.73% to the greatest extent, and the fouling resistance of cooling water in the heat exchanger increases up to 25.6% in different water conditions. When the sediment concentration and the turbidity in the river water are no more than 100 g/m3 and 50 NTU respectively, the performance of the heat pump is better, which can be used as a suitable river water quality standard for river water source heat pumps.

In view of the insufficiency of central air-conditioning system that FCU, water pumps and air blower’s movement connot match with the actual operating load when varying duty, an energy saving control system for central air-conditioning based on terminal temperature measuring and frequency conversion control technology is proposed. This system can real-time measure different floors’ and nods’ temperatures in the building, and export orders to control the frequency of FCU, chilled water pump, cooling water pump and cooling tower air blower. To overcome big delay, large inertia and variable condition of control object, the dnamic fzzy nural network algorithm(DFNN), is applied into the control system. According to the practical running situations, the energy saving control system has advantages as high energy saving rate, high stability, good maintainability, which may be promoted the application vigorously.