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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

Beredning av köldbärare för komfortändamål i kontorsverksamhet : En studie i produktionsslag / Preparation of secondary refrigerants for comfort purposes in office premises

Rolin, Jacob, Vestberg, Pontus January 2014 (has links)
The real estate company Ihus is facing an expansion of its comfort cooling in Noatun,Uppsala, to provide the buildings in the block with cooling. The buildings in Noatunare mainly used for office premises, where the requirements for an accepted indoorclimate is great. However, it’s uncertain whether Ihus should continue, as currently,producing comfort cooling by themselves using a compressor chiller, or if they shouldconnect themselves to Vattenfall’s district cooling net. The purpose of this report is to examine which technique of cooling is best suited forIhus and their buildings in Noatun. It should also work as a guideline for othercompanies facing the same problem as Ihus. In addition, the result should give an ideaof how cooling by using compressor chillers compares to district cooling in aneconomical perspective, aswell as in an environmental and performance perspective. This report is based mainly on studies of literature covering cooling, approximationsof contractor costs with the help of the calculation tool Wikells Sektionsdata andassays of life cycle costs for different refrigeration alternatives. The result is showing that refrigeration by using compressor chillers seems to be themost advantageous option for the buildings in Noatun. Investments of a newcompressor chiller and associated components to cover the cooling demand in theblock appears to be a better option than district cooling.The costs of district cooling varies greatly depending on its origin and geographicallocation. Because of these great variations, it’s difficult to come to a conclusion onwhat type of comfort cooling is the least expensive in all situations. Every uniquesituation requires an investigation.In order to determine the impact on the environment for each type of comfortcooling a more thoroughly analysis is required. However, district cooling is likely tobe a better option regarding the environmental impact due to a centralizedpreparation of the refrigerants. A centralized preparation allows easier environmentalefficiency work since it’s easier to oversee emissions in one large facility than in manysmaller ones. The performance of different types of comfort cooling has shown to be too difficultto compare in this report. The reason for this is mainly because of limited access ofinformation regarding performance, but also because district cooling and cooling byusing compressor chillers differs greatly technically. Therefore, it’s difficult to conducta fair comparison of their performance.
2

Vätskekylaggregat : Optimering med Advanced Process Control

Rehnholm, Mats January 2020 (has links)
Den pågående globala klimatförändringen innebär att vi behöver minska utsläppen av växthusgaser till atmosfären för att inte äventyra kommande generationers möjlighet att leva på jorden. Där har energieffektivisering blivit allt viktigare för företag för att minska utsläppen av växthusgaser vilket även innebär att man blir konkurrens­kraftig på marknaden.  Genom energieffektivisering minskar man sin förbrukning, vilket också innebär att man spar på förlusterna för transport av energin från produktion till förbrukning, det innebär vinning för miljön, samhäller och företaget. Berendsen är ett företag där effektivisering av sina processer är en ständigt pågående arbete för att spara på miljön och ekonomin. Ett område där det finns förbättringar och besparingar att göra är att undersöka ventilations- och kylsystemet som finns i anläggningen. Kylsystemet används för att kyla tilluften under sommarhalvåret, för att få en bra arbetsmiljö för de anställda. Under den andra halvan av året används kylmaskinen som värmepump för att spara energi. Målet med denna undersökning har varit att besvara frågorna om Advanced process control kan användas för att bestämma om vätskekylaggregatet i ventilationssystemet gör nytta i återvinnings­driften samt om det går att optimera driften av återvinningssystemet. Undersökningen genomfördes med hjälp av linjär regressionsanalys som är ett av flera verktyg i APC. Vidare har studien visat att verktyget i APC är användbar för att optimera driften av en process. / The ongoing global climate change means that we need to reduce greenhouse gas emissions to the atmosphere in order not to jeopardize the ability of future generations to live on earth. There, energy efficiency has become increasingly important for companies to reduce greenhouse gas emissions, which also means becoming competitive in the market. By improving energy efficiency, you reduce your energy consumption, which also means saving on the loss of energy transport from the product to the consumer, which means benefits for the environment, communities and the company. Berendsen is a company in which the efficiency of its processes is an ongoing work to save the environment and the economy. One area where there are improvements and savings to be made is to investigate the ventilation and cooling system that is in the plant. The liquid cooling unit is used to cool the supply air during the summer months, to provide a good working environment for the employees. During the second half of the year, the cooling machine is used as a heat pump to save energy. The aim of this study has been to answer the questions if Advanced process control can be used to determine whether the liquid cooling unit in the ventilation system is useful in the recovery operation and whether it is possible to optimize the operation of the recycling system. The study was conducted using linear regression analysis, which is one of several tools in APC. Furthermore, the study has shown that the tool in APC is useful for optimizing the operation of a process

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