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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Psychrometric Testing Facility Restoration and Cooling Capacity Testing

Cline, Vincent E. 2010 August 1900 (has links)
The Psychrometric Testing Facility at the Riverside Energy Efficiency Laboratory at Texas AandM University has not been operational for several years. The goal of this project was to restore the testing facility to a fully operational condition for the purpose of supporting research and cooling capacity testing, with the latter following the appropriate standards. Numerous changes were made to the coolant piping system, the data acquisition system, instrumentation, and temperature and humidity control to update and improve the facility. In addition, a computer program was developed and implemented that allows for flexible control of the facility’s conditions and collection of data while showing real time performance and refrigerant and psychrometric calculations. The current program flexibility, along with the proper combination of instrumentation, allows the Psychrometric Facility to operate with separate steady state environmental conditions in each room, according to, and meeting, the AHRI 210/240 standard. Cooling capacity testing done on a split system residential unit was compared to the published AHRI rating to benchmark the state of the facility. Tested cooling capacity was about 3 percent below the published cooling capacity; tested EER was about 7 percent below the published EER; and finally, the calculated SEER based on the default degradation coefficient was about 10 percent below the published SEER. The difference in the calculated performance parameters to the published are expected due to unknown testing conditions used to calculate the published rating.
2

Modeling of Solar-Powered Single-Effect Absorption Cooling System and Supermarket Refrigeration/HVAC System

Bahman, Ammar 01 January 2011 (has links)
This thesis consists of two different research problems. In the first one, the aim is to model and simulate a solar-powered, single-effect, absorption refrigeration system using a flat-plate solar collector and LiBr-H2O mixture as the working fluid. The cooling capacity and the coefficient of performance of the system are analyzed by varying all independent parameters, namely: evaporator pressure, condenser pressure, mass flow rate, LiBr concentration, and inlet generator temperature. The cooling performance of the system is compared with conventional vapor-compression systems for different refrigerants (R-134a, R-32, and R-22). The cooling performance is also assessed for a typical year in Tampa, Florida. Higher COP values are obtained for a lower LiBr concentration in the solution. The effects of evaporator and condenser pressures on the cooling capacity and cooling performance are found to be negligible. The LiBr-H2O solution shows higher cooling performance compared to other mixtures under the same absorption cooling cycle conditions. For typical year in Tampa, Florida, the model shows a constant coefficient of performance of 0.94. In the second problem, a numerical model is developed for a typical food retail store refrigeration/HVAC system to study the effects of indoor space conditions on supermarket energy consumption. Refrigerated display cases are normally rated at a store environment of 24ºC (75ºF) and a relative humidity of 55%. If the store can be maintained at lower relative humidity, significant quantities of refrigeration energy, defrost energy and anti-sweat heater energy can be saved. The numerical simulation is performed for a typical day in a standard store for each month of the year using the climate data for Tampa, Florida. This results in a 24 hour variation in the store relative humidity. Using these calculated hourly values of relative humidity for a typical 24 hour day, the store relative humidity distribution is calculated for a full year. The annual average supermarket relative humidity is found to be 51.1%. It is shown that for a 5% reduction in store relative humidity that the display case refrigeration load is reduced by 9.25%, and that results in total store energy load reduction of 4.84%. The results show good agreement with available experimental data.
3

Energy Usage prediction model comparing Indoor Vs. Outdoor Ice Rinks

Khalid, Waqas January 2012 (has links)
Indoor ice rinks use 1091 MWh per annum for ice hockey based on statistics from over 100 Swedish ice rinks (Stoppsladd, 2011).The refrigeration system contributes 35 to75%( (Rogstam, 2010) of total energy usage in ice rinks with average value of 43% (Stoppsladd, 2010) for indoor to 75% for outdoor ice rinks. The basic aim of project is to reduce energy consumption in Swedish ice rinks and scope is for indoor and outdoor ice rinks in cold and mild summer climatic conditions like Sweden. To achieve target of energy reduction in ice rinks actual heat loads on outdoor bandy ice rink are being estimated along with performance analysis of refrigeration machine. The refrigeration system, heat loads on ice surface and their correlation is studied and analyzed in detail for Norrtälje Outdoor bandy ice rink for four warm days and whole season 2010-2011. The tricky and significant task of validation of input climate data for accurate heat loads calculations is completed with Swedish Metrological & Hydrological (SMHI) climate model data, correlations and related web based geographical data. The heat loads (conductive, convective and radiant) on outdoor bandy ice rink are calculated through thermodynamic relations with validated input climate data and measurements where as refrigeration system performance is monitored and analyzed with ClimaCheck(CC) instrumentation. The average cooling capacity is calculated for four warm days by CC internal method and actual cooling energy produced is obtained by practically assumed COP of system with aid of MYCOM compressor software. The cooling capacity and heat loads on ice surface are compared and analyzed considering energy usage affecting parameters and weather parameters like temperature, wind speed, relative humidity and solar load. The convection and condensation are contributing 75%, radiation 18%, ice resurfacing 4% and ground and header heat gain 3% to total heat loads on ice sheet for whole season. The deviation between total cooling energy produced by refrigeration machine and total heat load energy is found 19% and 27% for four warm days and whole season 2010-2011.The deviation is due to overestimation of heat losses from compressor’s body, compressor’s on and off operations, overestimated radiation heat load due to unmeasured negative radiation and lack of actual ice resurfacing heat load evaluation. The developed model in MS Excel allows comparison of field climate data with SMHI model data, indoor and outdoor ice rinks in terms of predicted energy usage by refrigeration system and in total and acts as decision tool to choose for building an indoor/outdoor ice rink.
4

Performance analysis and validation of high-temperature cooling panels in passive geothermal system

JImenez Lopez, Carlos January 2018 (has links)
High Temperature Cooling, HTC, is a thermal conditioning strategy, which aims to reducemixing and transfer heat losses. Cooling capacity strongly depends on heat transfer coefficientsand offers a great response and several advantages in terms of efficiency and sustainability.Among the advantages, there is evidence that HTC offers an increment of energy efficiency ofHVAC systems, provision of healthier and more comfortable indoor climate and provide widepotentials for the applications of renewable. This principle leads to a higher energy efficiency ofwater-based radiant cooling systems.This paper intends to focus on the research of the thermal capacity and performance of a newalternative. This is where Cooling Radiant Ceiling Panels, CRCP, becomes a major innovationwithin the sector and begin to take on certain relevance. The cooling capacity curve of thisparticular CRCP panels has been only measured in an idealized room environment according toDIN EN 14240. Thus, further studies of this key parameter through climate chamber testingand Computational Fluid Dynamics simulations, CFD, are necessary. CFD particularly focuseson fluids in motion, their behavior and their influences in complex processes such as heat transfer.The fluid motion can be described through fundamental mathematical equations and it isbecoming widely used within the building sector.Two different cases are going to be investigated. The first case will determine the mostoptimal peripheral gap to enhance cooling performance through Natural Convection, NC. Thisstudy states the existence of a peripheral gap around the panels has proven to be inefficientin terms of enhancing natural convection in the climate chamber. The second case is aboutcalculating the cooling capacity as a function of the internal heat loads. The cooling capacity ofthe CRCP panels followed an expected behavior. The R-squared factor of the linear regressionwas found to be 0.986, hence, it does not affect the performance of the CRCP panels dependingon the inclusion of the IHLs.This thesis provides the necessary information for the implementation of CRCP panels anddifferent possible operating environments, including considerations, limitations and recommendationsfor future implementation of this strategy.
5

Resilient cooling technologies : Simulation study to determine the cooling capacity in old residentialbuildings located in mid-Sweden

Ali, Ali Talib January 2022 (has links)
The Long-term changes in the climate conditions have increased the need foradequate thermal comfort systems. These alternations influence extremeevents, which their intensity and frequency have increased over the past years.Moreover, this study focuses on space cooling and parameters that the systemshould have to be considered as resilient. Literature study was done to presentthe concept of resilience as well as the different methods used to provide spacecooling. In addition, the cooling systems suggested in this study, which aredistrict cooling and absorption cooling, were presented and explained.Furthermore, the study focuses on cooling demand in a group of residentialbuildings based on different thermal characteristics, which were implementedbased on building regulations from late 1960s to early 1980s. The buildingthermal properties were used as input to obtain their cooling demand by usingbuilding energy simulation tool. Based on the acquired results, an evaluationhas been made for the cooling demand of those buildings. Further analysispresented a correlation between the cooling demand and thermal properties ofthe buildings and aided in the determination of the required cooling capacity.The selection of the capacities was based on the resilience criterion as the systemhas to be able to provide adequate performance and safety for the occupantsduring extreme events. Furthermore, an assessment was done to compare thesuggested system based on their capacities and the primary energy use.
6

Optimalizace vzduchotechniky wellness sportovního centra / Optimization of air conditioning of the wellness sports center

Prchalová, Nikol January 2022 (has links)
The diploma thesis deals with microclimate of a pool hall. This is divided into three parts. The first part describes the theoretical aspects of the environment in swimming pools in general. The second part of the diploma thesis deals with the calculation of the course of specific moisture concentration during the day in the pool hall. Different humidity concentration curves are assessed based on different electable input parameters. Subsequently, suitable setting options are evaluated in order to achieve acceptable environment in the hall in terms of humidity and optimal operating costs. The last part relates to the experimental part. This examines the measurement of evaporation under different boundary conditions and the subsequent comparison with some calculation methods for the calculation of evaporation.
7

Составление методических указаний для внедрения программного обеспечения CFD-моделирования (вычислительной гидродинамики) в работу компании на примере анализа тепло-воздушного баланса цеха с тепловыделениями : магистерская диссертация / Drawing up guidelines for the implementation of CFD modeling software (computational fluid dynamics) in the work of the company on the example of the analysis of the heat-air balance of a workshop with heat releases

Бурдина, Т. А., Burdina, T. A. January 2022 (has links)
Рассмотрена возможность автоматизации расчетов в области кондиционирования воздуха. Изучено программное обеспечение CFD-моделирования. Проведено несколько расчетов и анализ полученных результатов. Разработаны методические указания по работе в программе для внедрения ее в работу компании. / Possibility of automation of calculations in the field of air conditioning is considered. Studied CFD modeling software. Several calculations and analysis of the obtained results were carried out. Guidelines for working in the program have been developed for its implementation in the work of the company.
8

Vliv obtokového součinitele na návrh a geometrii přímého výparníku pro chladící jednotku / The Effect of the Bypass Factor on Design and Geometry of the Evaporator for the Cooling Unit

Vytasil, Michal January 2016 (has links)
Diploma thesis focuses on effect of the bypass factor on design and geometry of the evaporator for the cooling unit of data centre. Effect of the bypass factor on individual design parameters is solved in detail. All dependendecies are captured by using graphs in which s placed a cement on that parameter. In part C, mathematical and physical solutions are demonstrated calculations and processes leading to the design of the exchanger. In the end, evaluation of the calculations is done and there is also showed possible improvements for the practise.

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