Applied Mechanics and Materials Vol. 525

Abstract: To investigate the relationships between heat transfer coefficient and baffle helix angle of double-helical baffles heat exchanger, the physical and mathematical model of double-helical baffles heat exchanger with different baffles helix angle were developed and carried out. The researched results show that the optimization baffles helix angle results in the highest heat transfer coefficient of double-helical baffles heat exchanger; the inlet flow flux of shell side has no effect on the optimization baffles helix angle for those heat exchanger with same heat transfer structure; The optimization baffles helix angle tends to decrease with the tube diameter increment of double-helical baffles heat exchanger.

Abstract: In recent years, liquid desiccant cooling system has shown its potential research value for its low-grade heat using and energy-saving. Thermal properties of liquid desiccant, especially its vapor pressure greatly affects the dehumidification efficiency of this system. Here comes the problem to find a liquid desiccant with better dehumidification effect and lower cost. To solve this problem, a local composition model: nonrandom two-liquid (NRTL) theory could be used to calculate a mixed solution of LiBr-CaCl₂, and calculates the ideal mixing ratio of this solution in a working environment. The best mixing ratio with cost-effectiveness can be worked out by taking into account the initial cost of the solution. Study shows that: compared to single LiBr solution, the dehumidification effect could be raised by more than 8.2% and the costs could be reduced by 20% with mixed LiBr-CaCl₂ solution.

Abstract: sewage heat exchanger is important to collect heat energy in sewage source heat pump system. Heat transfer enhancement effect is not obvious while the chemical methods and manual cleaning is applying to remove the heat exchangers fouling in the long-term operation. Here sets an ultrasonic incrustation removal physical model in heat exchanger structure to antiscaling and descaling simultaneously. The acoustic cavitation technology can be used in sewage source heat pump systems for the experimental results and decontamination rate reaches 50%.

Abstract: This paper studies the low temperature heat source heat pumps to improve the efficiency of the heat pump unit with economic principles and the use of compressed improve the working conditions of the compressor, and to explore the system operating mode. A new test run integrated heat pump system is designed. Heat pump system can be controlled by the intelligent control of the implementing agencies, to improve the economic system, the research of this paper can provide a potential basis for the efficient use of energy heat pump.

Abstract: This paper discussed the optimization of two cases of large scale heating and cooling system. One is the heating/cooling system with heating/cooling source with distance from load center, the other is the heating/cooling system with heating/cooling source located in the load center. The affect of the temperature difference between supply and return water, load density and the price of energy towards optimized radius and max radius was discussed using the existed model. The optimized radius and appropriate system parameters are got. It is a reference to the designers and operators related.

Abstract: It is a question if large scale heating/cooling network could be applied in China economically, environmental protection and energy saving. Toward this question, this paper studied the optimization of large scale heating and cooling network. The components of the system are analyzed and modeled in detail including heating/cooling source, heating/cooling users and transmit system. And the system can be optimized through the way of Life Cycle Cost, which compared the cost of large scale heating and cooling system with conventional system. The optimization also takes efficiency and economy in to consideration.

Abstract: In this paper, based on the Siemens S7-200 programmable controller in the central air conditioning control system, hardware and software of the central air-conditioning control system is designed. In hardware design PLC controller is used as controlling core to control temperature and humidity of the entire process. In the software design, control programming and multi-loop control of temperature, humidity PID algorithm are completed by using PLC programming software STEP7 because of its characteristics that it is easy to read and easy to achieve complete control. Lastly, Related parameter is set and the information is displayed by touching screen.

Abstract: A new IAQ improved ventilation system-reversible ventilation system was designed. This system's working principle was introduced. For analyzing the superiority of reversible ventilation system, the conceptions of effective fresh air ratio and minimum effective fresh air ratio were described. The formula of effective fresh air ratio was deduced. The formula can be used to analyze the different air outputs of reversible ventilation system and conventional general ventilation system, in rooms with the same degree of fresh air. It can be taken as the guide for design and actual applications of reversible ventilation system.

Abstract: With the rapid development of the rural economy, social progress and indoor heating methods also will be diversified, but given the limitations of technical means, resulting in lower rural energy efficiency, energy consumption is rising. To achieve the purpose of building energy efficiency in rural areas, two common ways of heating in rural areas are to compare. Select the same farm house kang - firewall and kang - soil heating in two different heating methods comparative analysis and apply fluid dynamics software to simulate two heating methods on the indoor temperature field, comparing two ways of heating of the room temperature at different heights .Kang firewall in a joint operation is better than kang - soil heating joint operation on indoor temperature distribution ,it was more uniform high comfort, you can save about 424Kg of standard coal annually. Compared to soil heating that firewall has a higher thermal efficiency and it is an energy efficient way of heating buildings in rural. Firewall heating consistent with sustainable development concept, which use renewable energy as fuel for lower cost. In-depth study can be important for social, environmental and economic value.

Abstract: An actual condition survey was conducted based on literature review and a questionnaire survey in this study. In a literature review, the overview and characteristics of the Korean boiler market were investigated and the efficiency of the boilers used in Korea was organized. A questionnaire survey was prepared on the basis of these contents. A questionnaire survey was conducted for 2,250 households in Korea. An analysis was made on the basic information such as the family members, income level, residential area and living floor area of survey respondents as well as boiler status such as the possession and use of boilers, a boiler replacement cycle and fuel expenses. Lastly, the implications for the spread of high-efficiency boilers were identified based on the types of boiler possession and the use characteristics of boilers by housing type.