Advanced Materials Research Vols. 732-733

Abstract: By comparing the three kinds of design of air conditioning system, and economic analysis, ground source heat pump system is selected to design the multi-storey office building and multilayer restaurant selection.

Abstract: This paper presents a mathematical model for simulating the heat transfer process in a cold-storage plate that can be used in the refrigerator vehicle. The numerical method studied was an enthalpy method. Variation rule between process of release cool and influenced factors were obtained. The effect of solar radiation time was investigated in discharging process. Both increasing the number of cold-storage plate and improving sealed performance of door and compartment can extend release cool time. The results show that according to the different breath heat of goods, reasonable arrangement of number of cold-storage plate can meet cold demand in the transport; solar radiation also has influence to the process of cold-storage plate release cool, with considering cold load caused by solar radiation, release cool time is shortened by 13%.

Abstract: The heat transfer and pressure drop characteristics for water flowing in four spiral coils with different shapes and different sizes were experimental studied. Reynolds number range from 4000 to 9000, volume flow rate range from 200 to 350 L/h and heating power range from 80-350 W. Based on the experimental results, the regularity of Reynolds number and heating power influencing on heat transfer and pressure drop characteristics was analyzed and discussed. The results indicate: the Nu increases with increasing Re, the greatest average heat transfer coefficient appears in the smaller circular spiral coil. The heat transfer coefficients increase with increasing heating power, the greatest average heat transfer coefficient also appears in the smaller circular spiral coil. The pressure drops increase with increasing Re, the pressure drop in big ellipse spiral coil is greatest. The resistance coefficients gradually decrease with increasing Re. The resistance coefficient of small circular spiral coil is always greatest, and the resistance coefficient of big circular spiral coil is smallest.

Abstract: Large-scale detailed survey and summarized on the heating present Situation of Shenyang City. Analyze and discuss the existence of the problems. Shenyang heating is still mainly coal-fired boilers in winter. The heating planning and district heat-supply detail planning should be made on the basis of city heating present situation. Adjust the unreasonable heat source and the energy structure, rearrange the unreasonable urban heating supply network, and plan the urban heating scientifically and reasonably. Control the emissions of coal-fired boilers indicators, strengthen the optimization of the efficiency of coal-fired boilers, to achieve the national energy saving and emission-reduction standards, and to promote the sustainable development of city heating.

Abstract: Established a hierarchy structure model and made a quantitative assessment of seven air-conditioning systems which are gas boiler plus electric refrigerating system、air-cooled heat pump、variable refrigerant volume air conditioning、ground-source heat pump air conditioning、centralized heat-supply plus electric refrigerating、gas direct-fired machine、energy storage on relevant professionality and indoor environment,initial investment,operating costs,operation and management,environmental impact,energy consumption.Finally we obtained an optimal scheme,which agreed with that in practice.

Abstract: In the paper, changes of both outlet temperature and relative humidity of solar powered two-stage wheel desiccant air conditioning system are tested with time under the typical Tianjin summer condition. It is found that supply air temperature of the solar driven desiccant cooling system could steady below 21 degrees Celsius, and the relative humidity of it is more than sixty percent in most of time of the actual operation. When operating, the thermal coefficient of performance of the whole air conditioning unit is about 0.5, and the reliability of two-stage wheel desiccant air conditioning system is verified.

Abstract: A model reference adaptive control (MRAC) algorithm is proposed to the air-conditioning system of variable air volume (VAV) terminal units (VAV BOX). The study of temperature controlling parameters in room area (Zone) is based on Lyapunov stability theory. We built the simulation model in Matlab to validate the superior controlling performance and good energy saving effect of the algorithm. The research shows that the energy consumption release 60% ~70% in larger room. In modern building, the energy saving and comfort is very important, so the simulation has important engineering practical value.

Abstract: Coordination on load tap changers (OLTCs) voltage and reactive power compensators in area transmission power system is presented to improve efficiency and voltage variation using a novel optimum procedure technique. The novel optimum technique procedure used hybrid differential evolution (HDE) to coordinate the OLTCs setting and reactive power compensation for reducing line losses and voltage change rate. The objection function is selected total line loss under the limited range of OLTCs setting and reactive power compensation. The proposal design method is used to IEEE-30BUS power system to demonstrate the useful method. The result exhibits to less line losses and a little voltage variation.

Abstract: High penetration level of distributed generation (DG) connected to distribution network makes the protection and control in the traditional distribution network face great difficulties, so this paper proposed a protection and control technology based on advanced feeder terminal unit (AFTU). According to DGs capability and load, the scheme divides the distribution network into several zones in advance, each of which can operate in island mode. Circuit breakers (CB) together with AFTU are installed at the beginning of feeder, the border of two zones and the point of DG connection. AFTUs interconnect with each other through the fiber optic network. AFTU detects the local electrical quantities in real-time and exchanges information with others through the fiber optic network. It can locate the faulted zone quickly to achieve fault isolation and island operation according to local and neighboring information. The reclosing of CB and the control of reconnection of DG are also designed. The case analysis illustrates the feasibility of the proposed distributed protection and control scheme.

Abstract: Traditional FFT show good trait in steady-state harmonic testing, while it turn low accuracy when testing harmonic with voltage sag or transient, and can not illustrates the information on amplitude-time plane. The discrete wavelet transform is suitable for transient harmonic signals. However it is not intuitive and has more computing than FFT. Since both steady-state and transient components exist in power system, a new method of harmonic analysis algorithm based on Kaiser windowed FFT combing with Daubechies wavelet transform is proposed. The simulation results demonstrate this method possesses high accuracy and flexibility in harmonic detection.