Yuefen Gao

Applying LCA and fuzzy AHP to evaluate building energy conservation

Reducing energy consumption and environment pollution is an important part in energy sustainability. Building energy conservation evaluation will drive the application of the new energy conservation technology. For building an energy conservation evaluation, energy conservation and environment impacts in all stages of the life cycle should be assessed. In this paper, the fuzzy analytic hierarchical process method and life-cycle assessment theory are adopted for building energy conservation evaluation. Factors in different hierarchies are weighted with linguistic variables by pair-wise comparisons, and factors in the lowest hierarchy within the different second hierarchy factors are also evaluated by linguistic variables. The membership degrees and integrated evaluation values are calculated. Then an example is studied to illustrate the proposed approach. The validity of the proposed method is verified and it demonstrates the effectiveness and practicability of the proposed approach. The results provide guidance in evaluating building energy conservation and determining the energy conservation grade of the building.

Airflow distribution performance comparison of four desktop task air conditioning systems

Task conditioning aims to provide each occupant with personalized clean air direct to the breathing zone. Microenvironment of a typical office workplace consisting of different task air conditioning system, such as CMP (Computer monitor panel), MP (movable panel), Horizontal Desk Grill (HDG) and Vertical Desk Grill (VDG) are studied by numerical simulation. Numerical simulation by k-ɛ 3-D turbulent flow is separately conducted to study the influence of supply velocity on microenvironment of these four desktop task conditioning systems. Three task conditioning velocities, 0.8, 1.0, 1.2 m/s (for MP system: 0.6, 0.8, 1.0m/s) are studied. Temperature and, Draught Rating (DR) and Predicted Percentage of Dissatisfied (PPD) of the room and workstation are applied to study the performance of task air conditioning. The performances of these four task air conditioning system are compared based on the numerical results. According to simulated results, task air supplying performances of CMP is similar with that of MP, and performances of HDG and VDG are almost the same. Results also show that task conditioning can provide excellent working environment when supply velocity is well designed. The results can provide important references for system design, optimization of the task conditioning system.

Performance Evaluation for Micro-Turbine Using Modified TOPSIS With Objective Weights

Micro-turbine is paid more and more attention in scientific research and commercial application with the development of distribution generation (DG) in the global range. It is essential to make a synthetic and scientific evaluation on the performance of micro-turbine in order to promote the progress of the distributed generation technology using micro-turbine. This study presents the synthetic performance evaluation of micro-turbine. Some performance characters (rated capacity, generating efficiency, overall system efficiency, unit cost, fuel consumption, multi-fuel, NOx emission level, noises and life time) are chosen as evaluating criterions and some common micro-turbines are taken as evaluating objects in this paper. Considering the difficulty of fuzzy synthetic evaluation method in calculation of the multiple factors and the ignorance of the relationship among evaluating objects, a modified TOPSIS with objective weights is introduced and applied in performance assessment of the micro-turbines. Each criterion weight is calculated based on Shannon’s entropy concept. The evaluation result of the example shows that this approach is favorable for fuzzy synthetic evaluation of micro-turbine performance, particularly applicable for situations where reliable subjective weights from experts cannot be obtained. The evaluation results can also be as references for manufactures how to improve design of micro-turbines and for users how to make proper selection of micro-turbines.© 2009 ASME