Search

Copyright of Refrigeration Engineering & Technology is the property of Odesa National University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Energy efficiency projects deployment for Ukraine is one of the challenging task today. Ukrainian industry faces very complex environment for project development as well as its deployment within organization nowadays. UA Policy struggle to keep place on the European market to have possibility not only be a part of global policy but to go forward and to bring benefits for macro and micro economy. Fresh breath by integration energy systems within project management into business model of organization let to move closer to hold under control energy efficiency projects realization and avoid financial risks. Environmental policy and energy policy play crucial role for Ukrainian transformation into European player. Presented proactive plan provides possibilities to deliver the intended economic and environmental benefits of the Ukrainian energy labelling and ecological design directives. These directives are in use or are under development process by increasing the rates of compliance with their energy efficiency requirements. To start from the energy efficiency development process investigation in order to have possibilities to make corrections on the stage of modeling and design can bring benefits and reduce costs for end users. To evaluate the efficiency of heat exchangers, there are over 40 different private integral energy efficiency criteria. Such a number makes the estimation of heat exchangers not always objective and sufficiently definite, which does not allow to algorithmize the task of determining the efficiency of heat exchangers. On the foundation of the system element representation for the heat exchange network, the concepts of energy potential and energy efficiency of energy exchange are proposed. The obtained equations allow us to determine the efficiency of energy exchange not only for an element of the heat exchange network, but also for a complex system as a whole with a minimum of information about the system. [ABSTRACT FROM AUTHOR]

Copyright of Refrigeration Engineering & Technology is the property of Odesa National University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The nonlinear separation principle for adaptive with respect of rotor resistance variation indirect field oriented control of induction motors has been proven. The adaptive system is composed from globally exponentially stable torque-flux indirect controller and locally exponentially stable adaptive with respect to rotor resistance variations observer. It is shown that for bounded torque and flux reference trajectories adaptive controller with replacement of actual rotor resistance by estimated one guarantees locally asymptotically stable torque-flux tracking and resistance estimation. Correct rotor resistance estimation is achieved if persistency of excitation conditions are satisfied (electromagnetic torque is not zero or rotor flux vector modulus is not zero). Otherwise rotor current is zero and rotor resistance has no influence for system behavior. Experimentally it is shown that dynamic behavior of autonomous subsystems and in closed loop adaptive system is the same proving strong dynamic separations of the subsystems. References 6, figures 2. [ABSTRACT FROM AUTHOR]

A new design method of sliding mode flux observers which are invariant with respect to rotor resistance variations is presented. The observers allow designing the direct field-oriented control algorithms of induction motors with invariance properties and therefore improved dynamic performance and energy efficiency. It is proved that observer is globally exponentially stable under accurate rotor resistance information and locally exponentially stable under limited parameter variations. Experimentally shown, that in comparison with existing robust vector control algorithms, the proposed solution allows achieving strong robustness properties with respect to rotor parameter variations. The improved robustness properties are guaranteed in full motor operating range, including zero speed. References 9, figures 6. [ABSTRACT FROM AUTHOR]