The application of DC grids is gaining more attention in office applications. Especially since powering an office desk would not require a high power connection to the main AC grid but could be made sustainable using solar power and battery storage. This would result in fewer converters and further advanced grid utilization. In this paper, a sustainable desk power application is described that can be used for powering typical office appliances such as computers, lighting, and telephones. The desk will be powered by a solar panel and has a battery for energy storage. The applied DC grid includes droop control for power management and can either operate stand-alone or connected to other DC-desks to create a meshed-grid system. A dynamic DC nano-grid is made using multiple self-developed half-bridge circuit boards controlled by microcontrollers. This grid is monitored and controlled using a lightweight network protocol, allowing for online integration. Droop control is used to create dynamic power management, allowing automated control for power consumption and production. Digital control is used to regulate the power flow, and drive other applications, including batteries and solar panels. The practical demonstrative setup is a small-sized desktop with applications built into it, such as a lamp, wireless charging pad, and laptop charge point for devices up to 45W. User control is added in the form of an interactive remote wireless touch panel and power consumption is monitored and stored in the cloud. The paper includes a description of technical implementation as well as power consumption measurements.
TheUniversity of Twente, SaxionUniversityofAppliedSciences, ROCofTwente(vocationaleducation), centre of expertise TechYourFuture and the H2Hub Twente, in which various regional hydrogen interested corporations are involved, work together to shape a learning community (LC) for the development of innovative hydrogen technology. The cooperation between company employees, researchers and students provides a means to jointly work on solutions for real-life problems within the energy transition. This involves a cross-chain collaboration of technical programs, professorships and (field) experts, supported by human capital specialists. In the LC, a decentralized hydrogen production unit with storage of green hydrogen is designed and built. The main question for this research is: how can the design and construction process of an alkaline electrolyzer be arranged in a challenge based LC in which students, company employees (specialists) and researchers from the three educational institutions can learn, innovate, build-up knowledge and benefit? In this project the concept of a LC is developed and implemented in collaboration with companies and knowledge institutions at different levels. The concrete steps are described below: 1. Joint session between Human Resource and Development (HRD) specialists and engineers/researchers to explore the important factors for a LC. The results of this session will be incorporated into a blueprint for the LC by the human capital specialists. 2. The project is carried out according to the agreements of the blueprint. The blueprint is continuously updated based on the periodic reflections and observed points for improvement. 3. Impact interviews and periodic reflection review the proceeding of the LC in this engineering process. The first impact interview reveals that the concept of the LC is very beneficial for companies. It increases overall knowledge on hydrogen systems, promotes cooperation and connection with other companies and aids to their market proposition as well. Students get the opportunity to work in close contact with multiple company professionals and build up a network of their own. Also the cooperation with students from different disciplines broadens their view as a professional, something which is difficult to achieve in a mono-disciplinary project.
MULTIFILE
Thermal comfort is determined by the combined effect of the six thermal comfort parameters: temperature, air moisture content, thermal radiation, air relative velocity, personal activity and clothing level as formulated by Fanger through his double heat balance equations. In conventional air conditioning systems, air temperature is the parameter that is normally controlled whilst others are assumed to have values within the specified ranges at the design stage. In Fanger’s double heat balance equation, thermal radiation factor appears as the mean radiant temperature (MRT), however, its impact on thermal comfort is often ignored. This paper discusses the impacts of the thermal radiation field which takes the forms of mean radiant temperature and radiation asymmetry on thermal comfort, building energy consumption and air-conditioning control. Several conditions and applications in which the effects of mean radiant temperature and radiation asymmetry cannot be ignored are discussed. Several misinterpretations that arise from the formula relating mean radiant temperature and the operative temperature are highlighted, coupled with a discussion on the lack of reliable and affordable devices that measure this parameter. The usefulness of the concept of the operative temperature as a measure of combined effect of mean radiant and air temperatures on occupant’s thermal comfort is critically questioned, especially in relation to the control strategy based on this derived parameter. Examples of systems which deliver comfort using thermal radiation are presented. Finally, the paper presents various options that need to be considered in the efforts to mitigate the impacts of the thermal radiant field on the occupants’ thermal comfort and building energy consumption.