Xutao Zhang

Multihierarchical Gray Evaluation Method to Assess Building Energy Conservation

The building sector is one of the fastest growing in terms of energy consumption. To guarantee energy savings and to reduce carbon dioxide (CO2) emissions, building energy conservation assessment is an important option. A building energy conservation assessment will strongly promote development of the building’s thermal characteristics and application of new energy conservation technologies and products. Because of the unquantifiable and incomplete information of evaluation criteria, a multihierarchical gray evaluation methodology is proposed for building energy conservation assessment. To determine the weights of the factors, a linear combination weighting method combining an analytic hierarchical process (AHP) method and the technique for order preference by similarity to ideal solution (TOPSIS) method is proposed. The integrated assessment results and the integrated assessment values are calculated, and a building energy conservation star is proposed and determined. Then, an example is used to illustra...

Prospects of natural gas storage and transportation using hydrate technology in China

Natural gas is becoming a main source of town gas in China. It is difficult to supply natural gas by pipelines from gas fields to every city in China. To solve the problem, natural gas hydrate (NGH) technology is introduced in this paper. At the same time, NGH technology is compared with liquefied natural gas (LNG) technology and compressed natural gas (CNG) technology. We conclude that NGH technology has many particular advantages, such as moderate conditions of production and storage, simple technology and high security. A domestic NGH gas supply chain is proposed including the production of NGH, the road transportation of NGH, the regasification of NGH and the gas distribution. In addition, a cost analysis of NGH gas supply chain is made compared with LNG gas supply chain. The result shows that the gas supply technology via NGH is more cost effective and has powerful competitive in China. Considering the technical advantages and the economic efficiency of NGH technology, we conclude that it has a bright application prospect in China and put forwards some suggestions on realizing the commercial application of NGH technology.

An illustration of the optimization of combined cooling heating and power systems using genetic algorithm

The performances of combined cooling, heating and power (CCHP) system are greatly dependent on its design, operation strategy and thermal and electric demands. This paper illustrates how the use of a genetic algorithm can provide speedy optimization, by applying it to two styles of buildings operated in different operation strategies. The primary energy consumptions of CCHP system following electric demand management (EDM) and thermal demand management (TDM) are firstly analyzed respectively. Then, sixteen hypothetical buildings are constructed to represent various energy demands. Primary energy saving (PES), annual total cost saving (ATCS), and CO2 emission reduction (CO2ER), are weighted to evaluate the integrated performances of CCHP system in comparison to separation production system. Finally, the optimized CCHP system for sixteen scenarios using GA are compared. Practical application: This paper provides an optimization design method for CCHP system. The performance analysis of CCHP systems running different operation modes for different buildings is believed by the authors to contribute to a significant guide for the fundamental design of CCHP systems. Although sensitivity to a number of other important design considerations such equipment performance, possible future changes in operating conditions, changes to the price or carbon intensity of grid-supplied energy etc are not addressed, the conclusions present a simple and effective direction and the proposed optimization algorithm and the evaluation method for CCHP system can be extended to other buildings.

Experiment on Hg 0 removal from flue gas by sodium chlorite solution

The important to enhancing gaseous elemental mercury (Hg0) removal in wet scrubber systems is altering the chemical form of the Hg0 to a water-soluble oxidized species. Experiments on the removal elemental mercury from simulated flue gas by aqueous sodium chlorite in a bubble reactor were carried out in this work. The effect of initial oxidizing solution concentration, reaction temperature, pH and SO2 concentration on mercury oxidative absorption in sodium chlorite were investigated. The results indicate that the higher concentration of sodium chlorite favors Hg0 removal, whose efficiency is greater in acidic than alkaline solution. High temperature inhibits Hg0 absorption in aqueous sorbent when reaction temperature is lower than about 40□, and the removal efficiency increases whereas temperature is higher than about 40□. The SO2 concentration did not significantly affect the efficiency of Hg0 removal.

Study on zero discharge technology of wastewater from power plant

This electronic document is a “live” template. The various components of your paper [title, text, heads, etc.] are already defined on the style sheet, as illustrated by the portions given in this document. About 60 percent or 70 percent of the cities in China are short of water in different degree, thus the water resource is very shortage in China. The problem of water shortage has restricted the industrial development. The matter is especially severe in North China and the area with water shortage areas. It is critical to increase the concentrated ratio of the circulating cooling water and decrease the wastewater discharge for the power plant, where the circulating cooling water system is used. According to the characteristic of the wastewater in the power plant at present, the problems of the optimization of the wastewater treatment are put forward in this paper. Whats more, the technology of staged concentration of circulating water used for supplying water is designed, viz. the circulating cooling water is concentrated in stages and operation in series with the supplying water. The practical engineering experience in a certain power plant, indicates that it is profitable for the technology of the supplying water being series-wound concentrated stepwise. With the use of this technology, the number of the discharge of wastewater is reduced, all of which reveals the social, economical and environmental benefits.

Study on treated wastewater from power plant as circulating supplementary water

The water consumed by power plants is about half of the total annual industrial water consumption in China. Considering some characteristics of wastewater in power plants, the paper presented a new process to treat the wastewater. In the process, wastewater was made centralized treatment utilizing activated sludge firstly, then water purifying agent was put into the wastewater and they were coagulation sedimentation. The wastewater was treated by aeration and disinfection at last. In order to increase the efficiency, the ash conveying water was used as the cogulating aid in the process. The experimental results showed that the presented process was effective. The quality of the wastewater after treated was stabile and the ash conveying water was beneficial to the flocculation promotion. The effluent was well used for the circulating cooling water system. It can be concluded that the wastewater of power plants can be the supplementary water of the circulating cooling water system after appropriate treatment. The engineering practice indicated that the process can reveal the social, economical and environmental benefits and be helpful to the realization of the zero discharge of the power plants.

Analytical design of decoupling control for variable flow hydronic heating system

Hydronic heating systems are used in homes and apartments worldwide. The variable flow system is advantaged to the energy saving while the control in variable flow system is difficult. This paper describes the typical variable flow hydronic heating system and presents the coupling mathematical model of heat exchanger. Based on the mathematical model, a new analytical design method of decoupling controller matrix is proposed in terms of the standard internal model control structure for variable flow hydronic heating system. Its advantage is that absolute decoupling for the nominal responses of system outputs can be implemented, and moreover, the controller parameters can be tuned on-line in a monotonous manner to cope with the perturbed plant dynamics, so that significant decoupling regulation can be achieved. The detailed simulation shows that the decoupling control system is effective and feasible.

Thermodynamics Performance Study on Air Source Heat Pump in Variant Operating Condition

A certain product of the air source heat pump is selected as the study object in the paper. By variant condition operating performance of such air source heat pump in variant condition of the air source heat pump offered by manufacturer, the thermodynamics analyses are made based on the first law of thermodynamics and exergy analyze theory. Coefficient of Performance (COP) and exergy efficiency in variant operating condition are calculated, and then the curves for the relationship of COP and exergy efficiency with the outlet temperature of the chilling water/heating water and the environment temperature are plotted. The COP functions concerning with the outlet temperature of the chilling water/heating water and the environment temperature are fitted. Conclusions on variant condition and operation of the air source heat pump are drawn by comparing these two theories. Finally, it indicates that the best operating condition should be set considering COP, exergy analysis and practical requirement for cold and thermal.

An Integrated Evaluation Method for Energy Supply System

The introduction of sustainable energy systems is strongly associated to what choices real estate owners make among different energy supply system options. This paper reviews briefly the evaluation criteria and methods of energy supply system, from technical, economical, environmental and social aspects. A new methodology for the integrated evaluation of the energy supply system’s feasibility is presented, which adopts the grey relational analysis method. As an example, three energy supply systems to provide cooling, heating and power to users are synthetically evaluated and compared in multi-criteria. The weights, used in multi-criteria evaluation, is discussed and suggested. The results prove that the grey relational analysis is an effective tool for decision making compared to single criteria evaluation.Copyright

Performance Value Index of the Solar Air-Conditioning System-PVI

Presently, the performance of the air-conditioner or the air-conditioning system is usually valued based on some performance indices. However, it is deficient to evaluate the performance of the air-conditioning system which uses the new energy or renewable energy only based on the indices mentioned above. According to the defects and based on the works of the solar application, a new index defined PVI is put forward to evaluate the performance of the solar air-conditioning system rationally, which is significant to the new energy or renewable energy application.Copyright