Design optimization of short-stroke single-phase tubular permanent-magnet motor for refrigeration applications

This paper describes a design methodology to achieve optimal performance for a short-stroke single-phase tubular permanent-magnet motor which drives a reciprocating vapor compressor. The steady-state characteristic of the direct-drive linear-motor compressor system is analyzed, an analytical formula for predicting iron loss is presented, and a motor-design procedure which takes into account the effect of compressor loads under nominal operating condition is formulated. It is shown that the motor efficiency can be optimized with respect to two leading dimensional ratios. Experimental results validate the proposed design methodology. Copyright © 2010 IEEE.

Tubular and sector heat pipes with interconnected branches for gas turbine and/or compressor cooling

Designing turbines for either aerospace or power production is a daunting task for any heat transfer scientist or engineer. Turbine designers are continuously pursuing better ways to convert the stored chemical energy in the fuel into useful work with maximum efficiency. Based on thermodynamic principles, one way to improve thermal efficiency is to increase the turbine inlet pressure and temperature. Generally, the inlet temperature may exceed the capabilities of standard materials for safe and long-life operation of the turbine. Next generation propulsion systems, whether for new supersonic transport or for improving existing aviation transport, will require more aggressive cooling system for many hot-gas-path components of the turbine. Heat pipe technology offers a possible cooling technique for the structures exposed to the high heat fluxes. Hence, the objective of this dissertation is to develop new radially rotating heat pipe systems that integrate multiple rotating miniature heat pipes with a common reservoir for a more effective and practical solution to turbine or compressor cooling. In this dissertation, two radially rotating miniature heat pipes and two sector heat pipes are analyzed and studied by utilizing suitable fluid flow and heat transfer modeling along with experimental tests. Analytical solutions for the film thickness and the lengthwise vapor temperature distribution for a single heat pipe are derived. Experimental tests on single radially rotating miniature heat pipes and sector heat pipes are undertaken with different important parameters and the manner in which these parameters affect heat pipe operation. Analytical and experimental studies have proven that the radially rotating miniature heat pipes have an incredibly high effective thermal conductance and an enormous heat transfer capability. Concurrently, the heat pipe has an uncomplicated structure and relatively low manufacturing costs. The heat pipe can also resist strong vibrations and is well suited for a high temperature environment. Hence, the heat pipes with a common reservoir make incorporation of heat pipes into turbo-machinery much more feasible and cost effective.

PHC Production Management System Based on RFID

At present, in large precast concrete enterprises, the management over precast concrete component has been chaotic. Most enterprises take labor-intensive manual input method, which is time consuming and laborious, and error-prone. Some other slightly better enterprises choose to manage through bar-code or printing serial number manually. However, on one hand, this is also labor-intensive, on the other hand, this method is limited by external environment, making the serial number blur or even lost, and also causes a big problem on production traceability and quality accountability. Therefore, to realize the enterprise’s own rapid development and cater to the needs of the time, to achieve the automated production management has been a big problem for a modern enterprise. In order to solve the problem, inefficiency in production and traceability of the products, this thesis try to introduce RFID technology into the production of PHC tubular pile. By designing a production management system of precast concrete components, the enterprise will achieve the control of the entire production process, and realize the informatization of enterprise production management. RFID technology has been widely used in many fields like entrance control, charge management, logistics and so on. RFID technology will adopt passive RFID tag, which is waterproof, shockproof, anti-interference, so it’s suitable for the actual working environment. The tag will be bound to the precast component steel cage (the structure of the PHC tubular pile before the concrete placement), which means each PHC tubular pile will have a unique ID number. Then according to the production procedure, the precast component will be performed with a series of actions, put the steel cage into the mold, mold clamping, pouring concrete (feed), stretching, centrifugalizing, maintenance, mold removing, welding splice. In every session of the procedure, the information of the precast components can be read through a RFID reader. Using a portable smart device connected to the database, the user can check, inquire and management the production information conveniently. Also, the system can trace the production parameter and the person in charge, realize the traceability of the information. This system can overcome the disadvantages in precast components manufacturers, like inefficiency, error-prone, time consuming, labor intensity, low information relevance and so on. This system can help to improve the production management efficiency, and can produce a good economic and social benefits, so, this system has a certain practical value.

Tubular and Sector Heat Pipes with Interconnected Branches for Gas Turbine and/or Compressor Cooling

Designing turbines for either aerospace or power production is a daunting task for any heat transfer scientist or engineer. Turbine designers are continuously pursuing better ways to convert the stored chemical energy in the fuel into useful work with maximum efficiency. Based on thermodynamic principles, one way to improve thermal efficiency is to increase the turbine inlet pressure and temperature. Generally, the inlet temperature may exceed the capabilities of standard materials for safe and long-life operation of the turbine. Next generation propulsion systems, whether for new supersonic transport or for improving existing aviation transport, will require more aggressive cooling system for many hot-gas-path components of the turbine. Heat pipe technology offers a possible cooling technique for the structures exposed to the high heat fluxes. Hence, the objective of this dissertation is to develop new radially rotating heat pipe systems that integrate multiple rotating miniature heat pipes with a common reservoir for a more effective and practical solution to turbine or compressor cooling. In this dissertation, two radially rotating miniature heat pipes and two sector heat pipes are analyzed and studied by utilizing suitable fluid flow and heat transfer modeling along with experimental tests. Analytical solutions for the film thickness and the lengthwise vapor temperature distribution for a single heat pipe are derived. Experimental tests on single radially rotating miniature heat pipes and sector heat pipes are undertaken with different important parameters and the manner in which these parameters affect heat pipe operation. Analytical and experimental studies have proven that the radially rotating miniature heat pipes have an incredibly high effective thermal conductance and an enormous heat transfer capability. Concurrently, the heat pipe has an uncomplicated structure and relatively low manufacturing costs. The heat pipe can also resist strong vibrations and is well suited for a high temperature environment. Hence, the heat pipes with a common reservoir make incorporation of heat pipes into turbo-machinery much more feasible and cost effective.