The influence of uniform flow orifice on the effect of Naturally stratified Chilled water-storage tank
The widely use of cooled storage technology in our country will be an irreversible trend with the development and improvement of the TOU price policy. Naturally stratified Chilled water-storage is a very important cool storage technology. In this paper, the effect of using uniform flow orifice in naturally stratified water-storage with slotted pipe diffuser is studied by contrast experiments firstly. Then the cases with uniform flow orifice are simulated. Through the comparison of experimental data and simulation data, the correctness of the mathematical model is verified. Finally, the effect of water-storage is studied by simulation when the uniform flow orifice is set with different voltage drop. Conclusions can be obtained as follows: the layered effect is greatly improved by setting the uniform flow orifice; it is when the voltage drop of uniform flow orifice is in an appropriate range which is about ten to tens Pa that the improvement is obvious.
Measured and Modeled Charging of a Stratified Chilled Water Thermal Storage Tank with Slotted Pipe Diffusers
As part of ASHRAE Research Project 1185, field data from the constant flow rate charging of a stratified chilled water storage tank with double-ring octagonal slotted-pipe diffusers serving a university chilled water system were compared with results of a transient axisymmetric computational fluid dynamics (CFD) model. Charge processes at flows near design flow rate and 50% of design were modeled. Laminar and turbulent simulations were performed for a range of slot dimensions. Performance of the model was assessed by direct comparison of temperature profiles and by comparison of common thermal performance metrics, including thermocline thickness, lost capacity, and equivalent lost height. The inlet Richardson number based on slot hydraulic radius was found to have the strongest effect on model results. The model Richardson number giving best agreement with the lost height of the field data for near design flow rate was roughly an order of magnitude greater than the Richardson number of the actual diffuser. It is conjectured that this is due to inherent differences between the flow produced by multiple three-dimensional jets in the actual diffuser and the continuous slot of the axisymmetric model. The effect of turbulence varied from negligible to moderate as the Richardson number decreased.
Using Activity Theory in Developing Instructial Tools for Project Management Studies
Competence and skills of the project manager are significant to project success. The skills needed in project managersâ work cannot be learned only by reading the books or a lecture hall; one learns them by practice. Therefore, an important challenge for educational institutions is to develop pedagogical practices that allow students to participate in working life projects and to confront real-life problems. Project-based learning (PBL) offers a model that enables students to practice the skills and competences needed in working life projects by utilizing real-world work assignments in time-limited projects. Using PBL method alone does not necessarily guarantee learning result. In order to be successful, PBL method requires effective and competent supervision and guidance of students as well as appropriate tools for instruction. In this study the concepts from activity theory (AT) are applied to development tools for supervising project-based learning.