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Aquifer thermal energy storage (ATES) is a technology to sustainably provide space heating and cooling. Particularly in The Netherlands the number of ATES systems has grown rapidly in the past decade, often with the (re)development of urban areas. To meet objectives for greenhouse gas emission reduction the number of ATES systems is expected and required to further rise in future both in The Netherlands and elsewhere. To evaluate the lessons learned and the role of practical aspects in the Dutch development of ATES systems, in this study the geohydrological conditions and well characteristics for 331 (~15% of total) Dutch ATES systems are evaluated with respect to optimal well design for maximal thermal energy recovery. The study shows that well design of most (70%) ATES systems is suboptimal. The well design criteria that have been used thus far in practice, focus on allowing maximum flow/capacity, disregarding the effect of groundwater flow on efficiency and the effect of well design on subsurface space use. Instead, well design should be based on a more representative value for the storage volume that takes into account . Based on monitoring data and analysis of variations and uncertainties of the actual storage volume, a guideline is defined to reflect these in the storage volume used for design. Also a guideline for well design is introduced that accounts for both conduction and dispersion losses as well as advection losses in case of high ambient groundwater flow.

Methodologies for the analysis of value and comparing thermal storage concepts are presented. Value is a measure of worth and is determined by the cost of conventional fuel systems. Value data for thermal storage in large solar thermal electric power applications are presented. Thermal storage concepts must be compared when all are performing the same mission. A method for doing that analysis, called the ranking index, is derived. Necessary data to use the methodology are included.

Dit rapport is een beschrijving van een energetische, technische en economische evaluatie van warmteterugwinning uit een aquifer met elektrische warmtepompen op een vermeerde-ringsbedrijf van 3,5 ha glas in de praktijk, gedurende de periode van december 2001 tot december 2002. Aan de hand van de bevindingen van deze praktijkevaluatie, is een rendementsbere-kening gemaakt voor een normaal glastuinbouwproductiebedrijf met grondkoeling, waar al elektrische aangedreven koelmachines aanwezig zijn. Het rapport besluit met een aantal praktische aanbevelingen waarop te letten, indien een ondernemer warmteterugwinning met een aquifer overweegt.

AbstractAn analysis of thermal balance and daylight level in building residential zones is presented in the article. The evaluation is focused on influence of façade thermal insulation layers and multi glass pane windows on reduction of solar gains and daylight level in internal spaces. The evaluation was carried out as a computer simulation study run in software DesignBuilder. The simulation outputs provided information about optimal façade design for energy efficiency and convenient daylighting in buildings under temperate climatic conditions.

Předkládaná bakalářská práce se zabývá řešením energetické bilance rodinného domu a návrhem vhodné kogenerační jednotky. Vhodnost nasazení kogenerační jednotky do rodinného domu je posouzena dle ekonomické bilance za 15 let provozu. ; Katedra elektroenergetiky a ekologie ; Obhájeno ; Submited bachelor thesis deals with solution of energetic evaluation of a family house and with a propose of convenient cogeneration unit. The convenience of placement of cogeneration unit to a family house is evaluated according to economical evaluation after 15 years of operation.

The purpose of this report is to identify and selectively review previous work done on the evaluation and use of thermal energy storage systems applied to parabolic trough power plants. Appropriate storage concepts and technical options are first discussed, followed by a review of previous work.

Global energy demand is increasing every year dramatically, which results global warming due to increased greenhouse gas emissions. So, to be environmentally friendly and sustainable, Sweden’s energy policy targets to reach 100 % renewable energy share in 2040. Already, Sweden achieved 50 % renewable energy share in 2012 which was targeted to achieve by 2020. Integration of solar heating system in residential sector, for space heating (SH) and domestic hot water (DHW), was one of the reasons for this achievement. Considerably, several numbers of solar heating systems were installed in houses until 2011. Thus, solar heating system could be a step towards to reach 2040s target. In 2011, detached Swedish house was installed with solar combi-system (SCS) which was designed to use 53% of solar energy. The main aim of this thesis is to analyze the thermal performance of SCS and correlation with its simulated system performance which is done in five steps.First step is the collection of measured data from the system for specific period one year from April 2019 to March 2020 and determined other unknown energy values in that data. In the second step, unknown data are calculated using scientific equations with information from users and reliable assumptions. Consequently, the analysis of measured data shows huge uncertainties. It follows to the third step as sensitivity analysis to enhance the assumption values. Thus, analyzed results are tabulated with reliable parameters and solar fraction (SF) of the measured data is calculated. In the fourth step, SH of the house is considered as reference to build a system model in Polysun simulation software, and the modelled results are verified with analyzed results. In the final step, system model is simulated by changing one-year weather profile to 10 years average weather profile. Thus, analyzed results and simulated results are compared to evaluate the performance. The real system has the SF of 52 % after sensitivity analysis whereas the simulated system showed the SF with percentage difference around 15 %.

In modular uninterruptible power supplies (UPSs), several DC/AC modules are required to work in parallel. This structure allows the system to be more reliable and flexible. These DC/AC modules share the same DC bus and AC critical bus. Module differences, such as filter inductor, filter capacitor, control parameters, and so on, will make it possible for the potential zero sequence current to flow among the modules. This undesired type of circulating current will bring extra losses to the power semiconductor devices in the system, which should be paid special attention in high power application scenarios. In this paper, plug’n’play modules and cycle control are discussed and validated through experimental results. Moreover, potential zero sequence circulating current impact on power semiconductor devices thermal performance is also analyzed in this paper.

A large amount of energy is consumed by heating and cooling systems to provide comfort conditions for commercial building occupants, which generally contribute to peak electricity demands. Thermal storage tanks in HVAC systems, which store heating/cooling energy in the off-peak period for use in the peak period, can be used to offset peak time energy demand. In this study, a theoretical investigation on stratified thermal storage systems is performed to determine the factors that significantly influence the thermal performance of these systems for both heating and cooling applications. Five fully-insulated storage tank geometries, using water as the storage medium, were simulated to determine the effects of water inlet velocity, tank aspect ratio and temperature difference between charging (inlet) and the tank water on mixing and thermocline formation. Results indicate that thermal stratification enhances with increased temperature difference, lower inlet velocities and higher aspect ratios. It was also found that mixing increased by 303% when the temperature difference between the tank and inlet water was reduced from 80 °C to 10 °C, while decreasing the aspect ratio from 3.8 to 1.0 increased mixing by 143%. On the other hand, increasing the inlet water velocity significantly increased the storage mixing. A new theoretical relationship between the inlet water velocity and thermocline formation has been developed. It was also found that inlet flow rates can be increased, without increasing the mixing, after the formation of the thermocline.