Heating systems in residential buildings: combine district heating with exhaust air heat pumps : For economical and sustainable development

Den nuvarande EU-strategin för hållbar utveckling har som övergripande syfte att fastställa och utveckla åtgärder så att livskvaliteten ständigt kan förbättras, både för nuvarande och kommande generationer. En del i strategin är klimatmål som i första skedet sträcker sig till år 2020, dess medlemsstater ska då bland annat ha reducerat både sin energianvändning och sina utsläpp av växthusgaser med 20 %. I Sverige står bostad- och servicesektorn för 40 % av landets energianvändning, de har själva satt målet till 25 % besparing. Nya strategier och höjd energieffektivitet ska leda till att målet nås. Ett viktigt utvecklingsområde är uppvärmning av byggnader som står för 60 % av sektorns energianvändning. En stor del av bostadsbeståndet anses ha en energisparpotential på 20-50 %. Vid sidan av förbättringsåtgärder på bostäders klimatskal är val av värmesystem av stor vikt. Bland flerbostadshus står fjärrvärme för över 90 % av levererad värmeenergi. Genom att komplettera fjärrvärme med frånluftsvärmepump kan byggnadens energieffektivitet höjas och fastighetsägare kan göra en ekonomisk vinst i minskad mängd köpt energi. Fjärrvärmeleverantörer har svarat mot denna utveckling genom att förändra sina abonnemang så att värmesystemet blir överdimensionerat en stor del av året, därigenom blir värmepumpen överflödig. I denna fallstudie undersöks ett flerbostadshus i orten Grums, där frånluftsvärmepump redan installerats innan fjärrvärmeabonnemanget förändrades. Det nya abonnemanget innebär att fastighetsägare måste välja vilken maximal baseffekt de kan få levererad under året. En utredning är nödvändig för att säkerställa vilket val som ger en stabil och låg kostnad vid olika temperaturvariationer. Ur fastighetsägares perspektiv är problemet av ekonomisk karaktär, men denna studie undersöker även kombinationen fjärrvärme med värmepump med hänsyn till energianvändning och hållbarhetsmässig aspekt. Drivs värmesystemet på bästa sätt idag eller går det att hitta alternativa driftsätt som fungerar bättre? Målsättningen är primärt att reducera bränsleanvändning med 25 %, sekundärt minska koldioxidalstring och samtidigt sänka livscykelkostnaden för värmepumpen samt att i tredje hand reducera mängd köpt energi. Målen ska nås vid årsmedeltemperatur 5-7 ºC. För närvarande används frånluftsvärmepump som basvärme till radiatorkrets och varmvatten medan fjärrvärme täcker underskott av husets värmebehov. Nuvarande driftsätt jämförs med två alternativ. Alternativ 1 innebär byte till värmepump med mer effekt samt att fjärrvärme värmer tappvarmvatten, i övrigt körs värmesystem på samma sätt som förut. I Alternativ 2 ändras driftsätt så att fjärrvärmes baseffekt utnyttjas maximalt och värmepump körs då vald baseffekt inte täcker värmebehov. Frånsett att värmepump byts i ena fallet är inga ominstallationer nödvändiga. I studien används Microsoft Excel och varaktighetsdiagram för att utföra beräkningar. Resultaten visar att ingen av alternativen når fullständig måluppfyllelse, dock når alternativ 1 högre måluppfyllelse i och med att det primära målet (resursbesparing) i vart fall nås delvis. Studien visar att flerbostadshus, liknande referensobjektet, kan anpassa både drift av befintligt värmesystem och val av baseffekt (fjärrvärme) för att nå ekonomisk vinst. Ökad användning av fjärrvärme minskar indirekt koldioxidalstring men ökar resursanvändning. Byte av frånluftsvärmepump reducerar köpt energi vilket leder till minskad resursanvändning och bättre ekonomi, dock ökar elanvändning vilket ger marginellt tillskott av koldioxidalstring.The overall aim of the current EU strategy Sustainable Development is to identify and develop measures to ensure that quality of life can be constantly improved, both for present and future generations. A part of the strategy is the climate targets which in the first phase extend to 2020. Its Member States shall then have reduced both their energy use and greenhouse gas emissions by 20 %. In Sweden the residential and service sector stands for 40 % of the country's energy use, they have themselves set the target to 25 % savings. New policies and improved energy efficiency will lead to completion. An important area of development is the heating of buildings, which accounts for 60 % of the sector's energy use. A large part of the housing stock is considered to have an energy savings potential of 20-50 %. Next to the improvement of the building envelope, the selection of heating system is of great importance. More than 90 % of delivered heat energy to the apartment blocks in Sweden comes from district heating. By supplementing district heating with exhaust air heat pumps, the building's energy efficiency can be increased and building owners can make a financial gain in the reduced amount of purchased energy. District heating distributers have responded to this development by changing their subscriptions, making the heating system oversized much of the year, thereby the heat pump becomes more or less redundant. In this case study, the heating system of an apartment building in the town of Grums (Sweden) is of interest. The exhaust air heat pump was already installed before the district heating subscription was changed. The new district heating subscription implicates that property owners have to choose which maximum base effect they can get delivered all year round. An investigation is necessary to ensure that the selected option provides a stable and low cost at different temperature. From the property owner's perspective, the problem is of economic nature. This study however, concentrates on the combination of district heating with heat pumps seen from the energy use and sustainability aspect. Is the heating system working in the best way today, or it is possible to find alternative modes that work better? The target with this study is to find an operational mode that primarily will reduce fuel use by 25%, secondary will lower carbon dioxide generation and cut life-cycle cost of the heat pump and thirdly will reduce the amount of purchased energy. These targets must be achieved within the annual outside temperature of 5-7 ºC. Currently the exhaust air heat pump is used as basic heat, warming up radiators and domestic hot water while district heating covers the deficit of the house's heating demand. Current operating mode is compared with two alternatives. Option 1 involves a change of the heat pump, to one with more power, district heating will heat the domestic hot water and will continuously work as a backup for the heat pump. In Option 2, the operation mode is altered to optimize use of the district heating base effect, the heat pump runs only when the selected base effect does not cover the heating demand. Apart from that the heat pump is replaced in the first case, no reinstallation is required for these options. Study calculations are made by using Microsoft Excel and duration diagrams. The results shows that none of the options reach the targets completely, however, Option 1 is closer considering that the primary goal (saving resources) is reached in part. The study shows that heating systems in apartment buildings, similar to the reference object, can be adjusted as well as the choice of base effect (district heating) in order to successfully reduce environmental effects and/or achieve financial gain. Increased use of district heating indirectly reduces carbon dioxide generation but increases resource use. Replacement of exhaust air heat pump reduces purchased energy which leads to reduced use of resources and better economy, however, will increase electricity consumption, which gives a marginal addition contribution of carbon dioxide generation

Primary Hyperparathyroidism - Aspects on skeletal Involvemnt and PTH levels after Surgery.

The aim of this thesis was to evaluate risk factors for fractures in patients with primary hyperparathyroidism (pHPT), to study the association between preoperative variables and postoperative changes in bone density and to investigate long-term changes and peripheral PTH sensitivity in patients with elevated PTH levels after surgery. 203 pHPT patients were investigated with regard to clinical and biochemical variables and bone density. Serum levels of 25(OH)D3 and PTH, were the only variables independently associated with a risk of bone fracture. Thirteen patients with pHPT were investigated with a PTH infusion test six weeks after surgery. During the PTH-infusion test we found that patients with raised PTH had signs of decreased peripheral sensitivity to PTH with attenuated calcemic response. 99 pHPT patients were followed five years after surgery. 16% of the patients had elevated PTH levels. One group of patients that demonstrated fluctuation between normal and elevated PTH levels showed signs of renal insufficiency. In this group of patients, an increased risk for recurrent disease is postulated and long time surveillance could be suggested. Bone mass was investigated before and one year after surgery in 126 pHPT patients. Postmenopausal women had lower bone density compared to premenopausal women. 40-50% of all patients improved in bone density after surgery. It was not possible to predict the increase in bone mass. Considering that 18 % respectively 61% of patients had signs of vitamin D and calcium deficiency, we suggest that pHPT patients could be considered for calcium and vitamin D supplement postoperatively

Management of the exterior branch of the superior laryngeal nerve among thyroid surgeons - Results from a nationwide survey.

The external branch of the superior laryngeal nerve is important for the voice. However, it is unknown how thyroid surgeons manage this nerve during operations. We hypothesised that this management is related to the surgeon's age, gender, the surgeons' annual number of thyroid operations, i.e volume, and surgical specialisation

Technology and market study on continuous casting rolls

This Master’s Thesis consists of two separate and independent studies: One metallurgical study and one industrial buying behaviour study. Both studies concern continuous casting rolls. Metallurgical Study: The first objective of this study was to investigate two continuous casting rolls, consisting of different steel tubes with different martensitic stainless steel weld overlays. The second objective was to evaluate the methods employed in the study. The weld overlaps are clearly the weakest points of the weld overlay. They are sensitive to corrosion attacks, mainly due to sensitisation. The delta ferrite present in the welded overlay of both rolls is a preferential site for the corrosion attacks and the delta ferrite content depends primarily on the chemical composition of the weld overlay. The welding temperature may also have some influence on the delta ferrite content, but this has not been observed in this study. Both rolls have similar surface hardness. Roll no. 2 has more generalized corrosion attacks than roll no. 1. This is due to a higher delta ferrite content in roll no. 2 than in roll no. 1. The methods employed during the study proved to be adequate. In any future study, on condition that the visual inspection, diameter measurements, ultrasonic testing and surface hardness measurements show that all positions on the roll are similar, it will be sufficient to cut a bead and overlap sample from only one position. The rolls were investigated using macro etching, optical microscopy, Vickers hardness testing, ultrasonic testing ICP-OES analysis of nickel and chromium content and carbon content analysis by wet chemical method. Delta ferrite content was also calculated theoretically using a Schaeffler – DeLong diagram and a semi-empirical model. Industrial Buying Behaviour Study: The aim of this study is to investigate the industrial buying behaviour in slab casting steelworks in Western Europe when buying roll-lines. Case studies have been conducted at four steelworks belonging to different companies. Data was collected through personal interviews with people from production, maintenance and purchasing department and intermediate level management. A test consisting of a smaller amount of rolls is always performed before buying any larger quantities of rolls. Even though the test order has relatively low economic value, compared to a full-scale order, it is during this process that the relationships are established between the buying and the selling company. Findings show that the industrial buying behaviour of steelworks in Western Europe agrees well with the theory in this field. The buying process follows the steps in the buygrid model with only a few exceptions. The decision-making power lays in the intermediate level management, even though approval is required from upper level management. The most important factors affecting the buying behaviour are the relationship between the buyer and the seller, service-life and life cycle cost of the roll-line.Validerat; 20101217 (root

Biochemical diagnosis of primary hyperparathyroidism: Analysis of the sensitivity of total and ionized calcium in combination with PTH.

OBJECTIVES: To investigate the accuracy of the biochemical diagnosis of primary hyperparathyroidism (pHPT) in a consecutive series of patients with operatively verified disease. DESIGN AND SUBJECTS: Four hundred thirty-six patients with pHPT, 340 women and 96 men, were reviewed. Biochemical variables, including total calcium (Ca), ionized calcium (Cai) and PTH were analyzed and registered in a prospective database. RESULTS: In the subgroup of patients with more mild hypercalcemia (Ca below 2.70mmol/L) the correlation between Ca and Cai was poor. 19 respectively 18 patients had preoperatively a Ca respectively Cai level within the reference range. Further 35 patients had preoperatively a normal level of PTH. The diagnostic sensitivities for Ca, Cai and the combination of Ca and Cai were 96%, 96% and 99%. CONCLUSION: If calcium and ionized calcium are not used in the diagnostic workup of pHPT some 4% of the patients will be overlooked. We recommend analyzing both Ca and Cai in the diagnostic workup of pHPT

LCA OF LOCAL BIO-CHP FUELLED GREENHOUSES VERSUS MEDITERRANEAN OPEN FIELD TOMATOES FOR CONSUMPTION IN NORTHERN SCANDINAVIA

Tomatoes are a commonly used product in the Scandinavian countries, where locally grown tomatoes generally have to be cultivated in greenhouses, heated for most part of the year. Tomatoes imported from the Mediterranean area will not need heated greenhouses, but are transported a longer distance. Earlier studies have shown imported tomatoes over long distances are environmentally preferable when compared to tomatoes produced in greenhouses. In this study, tomatoes for the Trøndelag market in Norway locally grown in greenhouses with heat from biofuelled CHP generation have been studied using life cycle assessment (LCA). An LCA model for the biofuel heated greenhouse tomatoes was created and compared to a model of field grown tomatoes in Spain. In a sensitivity analysis a fossil energy scenario for the greenhouse tomatoes was studied. The biofuelled greenhouse tomatoes was found to be better in all studied life cycle impact categories compared to the long-distance transported field grown tomatoes. The scenario with fossil energy to the greenhouse give much higher impacts compared to the long distance transported tomatoes in most categories studied. A shift towards more renewable energy systems is one important task for a more sustainable agriculture

Determinants for malignancy in surgically treated adrenal lesions.

PURPOSE: It is difficult to definitively rule out or establish malignancy pre-operatively in patients with adrenal lesions referred for adrenal surgery. The aim of this study was to identify risk factors for a malignant diagnosis in patients treated with adrenalectomy. METHODS: Consecutive adrenalectomies at the Department of Surgery, Lund University Hospital between 2000 and 2009 were identified. Pre-operative clinical, radiological and biochemical data, as well as details on the operation and histology, were retrieved from patients' medical records. RESULTS: There were 175 adrenal operations in 172 patients (98 female and 77 male). There were 28 malignancies. Malignant tumours were larger than in benign cases (p = 0.003), had radiological signs of malignancy more often (p = 0.001) and the patients were more likely to have a history of malignancy (p = 0.001). There were no differences regarding age, gender, body mass index or mode of detection (incidental vs. clinical) between patients with benign and malignant diagnoses. A unilateral uptake on fluorine-18 deoxyglucose positron emission tomography was more frequent in malignant cases than in benign; however, this association did not reach statistical significance. CONCLUSIONS: Size of adrenal lesion, suspicious radiological findings and history of malignancy were factors associated with malignancy

Effect on bone density of postoperative calcium and vitamin-D supplementation in patients with primary hyperparathyroidism: A retrospective study.

BACKGROUND: Primary hyperparathyroidism (pHPT) is associated with decreased bone density and increased fracture risk. A significant number of pHPT patients have low calcium intake and suffer from vitamin deficiency. Thus, we adopted a policy of postoperative supplements with calcium and vitamin D after parathyroid surgery. In this study, we investigated if this policy enhanced the postoperative increase in bone density. PATIENTS/METHODS: Forty-two consecutive patients (83% female) were studied. The first 21 patients received no supplements, whereas the following 21 patients received 1,000 g calcium and 800 IU hydroxy D: -vitamin daily (Ca-D group) for 1 year postoperatively. The patients were monitored with bone density and biochemistry pre- and at 1 year postoperatively. RESULTS: Preoperatively, the patients without vitamin D supplementation (non-Ca-D group) did neither differ in biochemistry, clinical features, nor in bone density from patients in Ca-D group. Postoperatively, there was a tendency that patients in Ca-D group increased their bone density, at all sites measured, in a greater extent than patients that did not receive calcium and vitamin D supplementation. CONCLUSION: In conclusion, based on our results, it is difficult to give a recommendation of vitamin D supplementation in routine use following surgery for primary hyperparathyroidism. Based on the present data, a calculation of sample size for a future randomized controlled trial is presented