<p>Industrial living is caused much people do live and work in closed and confined places; offices and residential buildings. This is why in this new world more fresh air which is generally provided by forced ventilation plays a vital role in living of human being. Furthermore because of many different indoor pollutants, like radon and artificial pollutants, the amount of fresh air and in turn the energy consumption has increased. This energy consumption related to ventilation has reached up to about 30 percent of energy used of building section. So making interaction between indoor air quality (IAQ) and optimization of energy saving is a necessary work.  Radon as a natural pollutant is occurred in environment and in many countries threatens people health whereas is called the second causes of cancer. For reducing radon concentration in residential building at the acceptable level forced ventilation is used usually. Ventilation can improve IAQ but in the other side would increase the energy consumption in building sector and just now the contribution of ventilation exceeds up 50 percent of building sector's share. The aim of this thesis is to study the impact of ventilation on indoor radon by using Computational Fluid Dynamics (CFD) to achieve indoor air quality and energy efficiency. Application of CFD as a new technology, because of its cost and time savings, and on the other side, of its flexibility and precision is  increasingly grown and can be used as a very important and valuable tool for the prediction and measurement of radon distribution in a ventilated building . Currently, measurement techniques and proposed standards and regulations of indoor pollutants and ventilation, particularly related to indoor radon cannot be able to provide a secure, safe and energy efficient indoor climate. This is why the indoor airflow distribution is very complex and with changing building geometry and operation condition, the treatment of air flow pattern, substantially would be changed, whereas the rules are usually independent of the buildings features. Furthermore, the indoor standards and regulations are based on average amount of pollutants in a room, whereas the pollutant distributions aren't identical and are varied throughout the room. Then the current techniques aren't so exactly valuable and acceptable.</p><p>From different methods which is privilege to control pollutants, ventilation method is applicable in existing buildings. Designing effective ventilation can reduce radon concentration to very level low with regarding energy conservation remarks.</p><p> </p><p>This thesis presents results from simulation studies on ventilation and radon mitigation in residential buildings, in view points of indoor air quality and energy savings. The CFD technique is applied to predict, visualize and calculate of mixture radon-air flow. The distribution of indoor radon concentration, air velocity and room temperature also have considered together for achieving indoor air quality and energy saving. The results are also compared with the experimental data and related previous works.</p><p> </p><p>It was found that with increasing ventilation rate, the radon concentration is decreased, but the location of ventilation system is also important. From the simulation results, it is observed that within the ventilated room, there are some zones, which are good for living and somewhere is more polluted. The traditional radon detectors basically show the average value of radon content in 1m­³ of air. That is why detector measuring is not exact and safe.</p><p> </p><p>Simulation results proved that floor heat can be supported ventilation effect and speed up the mixture movement. Floor heating reinforces the buoyancy effect, which is useful to reduce radon content in the floor (seating area) and then lower ventilation rate can be applied.</p>

<p>Astra Zeneca plant in Gärtuna has many compression cooling machines for comfort that consume about 11.7 GWh of electricity per year. Many of the cooling machines are old; due to the increase of production of the plant, cooling capacity was limited and new machines have been built. Now, the cooling capacity is over-sized. Söderenergi is the district heating plant that supplies heating to Astra Zeneca plant. Due to the strict environmental policy in the energy plant, last year, a bio-fuelled CHP plant was built. It is awarded with the electricity certificate system.</p><p>The study investigates the possibility for converting some of the compression cooling to absorption cooling and then analyzes the effects of the district heating system through MODEST optimizations. The effects of the analysis are studied in a system composed by the district heating system in Södertälje and cooling system in Astra Zeneca. In the current system the district heating production is from boiler and compression system supplies cooling to Astra Zeneca. The future system includes a CHP plant for the heating production, and compression system is converted to absorption system in Astra Zeneca. Four effects are analyzed in the system: optimal distribution of the district heating production with the plants available, saving fuel, environmental impact and total cost. The environmental impact has been analyzed considering the marginal electricity from coal condensing plants. The total cost is divided in two parts: production cost, in which district heating cost, purchase of electricity and Emissions Trading cost are included, and investment costs. The progressive changes are introduced in the system as four different scenarios.<strong></strong></p><p>The introduction of the absorption machines in the system with the current district heating production increases the total cost due to the low electricity price in Sweden. The introduction of the CHP plant in the district heating production supposes a profit of the production cost with compression system due to the high income of the electricity produced that is sold to the grid; it profit increases when compression is replaced by absorption system. The fuel used in the production of the future system decreases and also the emissions. Then, the future system becomes an opportunity from an environmental and economical point of view. At higher purchase electricity prices predicted in the open electricity market for an immediately future, the future system will become more economically advantageous.</p><p> </p><p> </p>

<p>The aim of the project is to analyze the enlargement of the district heating line located in Gävle, evaluating the hydraulic facilities and calculating the heat losses with different insulation thicknesses to choose the best insulation thickness for the pipes. To choose the best thickness, different insulation thicknesses have been evaluated calculating the heat losses for each insulation thickness. To manage the heat losses problem, the pipe length has been divided into three</p><p>stretches, underground pipe, sea pipe and air pipe. These three stretches have different boundary conditions, and each stretch has been calculated separately. The best thermal solution is choosing the insulation of 0.5m of thickness, but the best thermal solution is not the best solution for this project due to the elevated cost of this thickness in one of the stretches of the line. The pipe crossing the seahas to be on the bottom and to keep the pipe on the bottom concrete is going to be added. The quantity of concrete needed depends on the floatability of the pipe and specifically depends on the insulation thickness. The insulation is a porous material and its density is very small, therefore it has a high floatability. The final</p><p>selection is a multi-thickness insulation, with different insulation thicknesses in the different stretches, 0.6m of thickness in the underground and air pipe and 0.3m of thickness in the sea pipe. With this configuration the heat losses are quite close to the optimum case. The purpose in the hydraulic study has been quantifying the start pressure in the new line to fulfil the energy demand in the worst point of the line. With 320kPa at the start of line, the pressure in the worst point is enough to fulfil the nowadays</p><p>demand, 3MW, and in the future when this line will be enlarged and the demand increased to 20MW, the pressure at the start of the line to ensure the requested pressure of 250kPa in the worst point should reach more than 380kPa. Having such pressure is not recommended to avoid the pressure hammer and to build a new pumping station after the sea pipe is recommended.</p>

Industrial living is caused much people do live and work in closed and confined places; offices and residential buildings. This is why in this new world more fresh air which is generally provided by forced ventilation plays a vital role in living of human being. Furthermore because of many different indoor pollutants, like radon and artificial pollutants, the amount of fresh air and in turn the energy consumption has increased. This energy consumption related to ventilation has reached up to about 30 percent of energy used of building section. So making interaction between indoor air quality (IAQ) and optimization of energy saving is a necessary work.  Radon as a natural pollutant is occurred in environment and in many countries threatens people health whereas is called the second causes of cancer. For reducing radon concentration in residential building at the acceptable level forced ventilation is used usually. Ventilation can improve IAQ but in the other side would increase the energy consumption in building sector and just now the contribution of ventilation exceeds up 50 percent of building sector's share. The aim of this thesis is to study the impact of ventilation on indoor radon by using Computational Fluid Dynamics (CFD) to achieve indoor air quality and energy efficiency. Application of CFD as a new technology, because of its cost and time savings, and on the other side, of its flexibility and precision is  increasingly grown and can be used as a very important and valuable tool for the prediction and measurement of radon distribution in a ventilated building . Currently, measurement techniques and proposed standards and regulations of indoor pollutants and ventilation, particularly related to indoor radon cannot be able to provide a secure, safe and energy efficient indoor climate. This is why the indoor airflow distribution is very complex and with changing building geometry and operation condition, the treatment of air flow pattern, substantially would be changed, whereas the rules are usually independent of the buildings features. Furthermore, the indoor standards and regulations are based on average amount of pollutants in a room, whereas the pollutant distributions aren't identical and are varied throughout the room. Then the current techniques aren't so exactly valuable and acceptable. From different methods which is privilege to control pollutants, ventilation method is applicable in existing buildings. Designing effective ventilation can reduce radon concentration to very level low with regarding energy conservation remarks.   This thesis presents results from simulation studies on ventilation and radon mitigation in residential buildings, in view points of indoor air quality and energy savings. The CFD technique is applied to predict, visualize and calculate of mixture radon-air flow. The distribution of indoor radon concentration, air velocity and room temperature also have considered together for achieving indoor air quality and energy saving. The results are also compared with the experimental data and related previous works.   It was found that with increasing ventilation rate, the radon concentration is decreased, but the location of ventilation system is also important. From the simulation results, it is observed that within the ventilated room, there are some zones, which are good for living and somewhere is more polluted. The traditional radon detectors basically show the average value of radon content in 1m­3 of air. That is why detector measuring is not exact and safe.   Simulation results proved that floor heat can be supported ventilation effect and speed up the mixture movement. Floor heating reinforces the buoyancy effect, which is useful to reduce radon content in the floor (seating area) and then lower ventilation rate can be applied.

HTML clipboard Numerical analysis of partial admission in axial turbines is performed in this work. Geometrical details of an existing two stage turbine facility with low reaction blades is used for this purpose. For validation of the numerical results, experimental measurements of one partial admission configuration at design point was used. The partial admission turbine with single blockage had unsymmetrical shape; therefore the full annulus of the turbine had to be modeled numerically. The numerical grid included the full annulus geometry together with the disc gaps and rotor shrouds. Importance of various parameters in accurate modeling of the unsteady flow field of partial admission turbines was assessed. Two simpler models were selected to study the effect of accurate modeling of radial distribution of flow parameters. In the first numerical model, the computational grid was two dimensional and the radial distribution of flow parameters was neglected. The second case was three-dimensional and full blades’ span height was modeled but the leakage flows at disc cavity and rotor shroud were neglected. Detailed validation of the results from various computational models with the experimental data showed that modeling of the leakage flow at disc cavities and rotor shroud of partial admission turbines has substantial importance in accuracy of numerical computations. Comparison of the results from two computational models with varying inlet extension showed that modeling of the inlet cone has considerable importance in accuracy of results but with increased computational cost. Partial admission turbine with admission degree of  ε = 0.524 in one blocked arc and two opposing blocked arcs were tested. Results showed that blocking the inlet annulus in one single arc produce better overall efficiency compared to the two blocked arc model. Effect of varying axial gap distance between the first stage stator and rotor rows was also tested numerically for the partial admission turbine with admission degree of  ε = 0.726. Results showed higher efficiency for the reduced axial gap model. Computations showed that the main flow leave the blade path down to the disc cavity and re-enter into the flow channel downstream the blockage, this flow would pass the rotor with very low efficiency. First stage rotor blades are subject to large unsteady forces due to the non-uniform inlet flow. Plotting the unsteady forces of first stage rotor blades for partial admission turbine with single blockage showed that the blades experience large changes in magnitude and direction while traveling along the circumference. Unsteady forces of first stage rotor blades were plotted in frequency domain using Fourier transform. The largest amplitudes caused by partial admission were at first and second multiples of rotational frequency due to the existence of single blockage and change in the force direction. Results obtained from the numerical computations showed that the discs have nonuniform pressure distribution especially in the first stage of partial admission turbines. The axial force of the first rotor wheel was considerably higher when the axial gap distance was reduced between the first stage stator and rotor rows. The commercial codes used in this work are ANSYS ICEM-CFD 11.0 as mesh generator and FLUENT 6.3 as flow solver. / QC20100622

Astra Zeneca plant in Gärtuna has many compression cooling machines for comfort that consume about 11.7 GWh of electricity per year. Many of the cooling machines are old; due to the increase of production of the plant, cooling capacity was limited and new machines have been built. Now, the cooling capacity is over-sized. Söderenergi is the district heating plant that supplies heating to Astra Zeneca plant. Due to the strict environmental policy in the energy plant, last year, a bio-fuelled CHP plant was built. It is awarded with the electricity certificate system. The study investigates the possibility for converting some of the compression cooling to absorption cooling and then analyzes the effects of the district heating system through MODEST optimizations. The effects of the analysis are studied in a system composed by the district heating system in Södertälje and cooling system in Astra Zeneca. In the current system the district heating production is from boiler and compression system supplies cooling to Astra Zeneca. The future system includes a CHP plant for the heating production, and compression system is converted to absorption system in Astra Zeneca. Four effects are analyzed in the system: optimal distribution of the district heating production with the plants available, saving fuel, environmental impact and total cost. The environmental impact has been analyzed considering the marginal electricity from coal condensing plants. The total cost is divided in two parts: production cost, in which district heating cost, purchase of electricity and Emissions Trading cost are included, and investment costs. The progressive changes are introduced in the system as four different scenarios. The introduction of the absorption machines in the system with the current district heating production increases the total cost due to the low electricity price in Sweden. The introduction of the CHP plant in the district heating production supposes a profit of the production cost with compression system due to the high income of the electricity produced that is sold to the grid; it profit increases when compression is replaced by absorption system. The fuel used in the production of the future system decreases and also the emissions. Then, the future system becomes an opportunity from an environmental and economical point of view. At higher purchase electricity prices predicted in the open electricity market for an immediately future, the future system will become more economically advantageous.

The aim of the project is to analyze the enlargement of the district heating line located in Gävle, evaluating the hydraulic facilities and calculating the heat losses with different insulation thicknesses to choose the best insulation thickness for the pipes. To choose the best thickness, different insulation thicknesses have been evaluated calculating the heat losses for each insulation thickness. To manage the heat losses problem, the pipe length has been divided into three stretches, underground pipe, sea pipe and air pipe. These three stretches have different boundary conditions, and each stretch has been calculated separately. The best thermal solution is choosing the insulation of 0.5m of thickness, but the best thermal solution is not the best solution for this project due to the elevated cost of this thickness in one of the stretches of the line. The pipe crossing the seahas to be on the bottom and to keep the pipe on the bottom concrete is going to be added. The quantity of concrete needed depends on the floatability of the pipe and specifically depends on the insulation thickness. The insulation is a porous material and its density is very small, therefore it has a high floatability. The final selection is a multi-thickness insulation, with different insulation thicknesses in the different stretches, 0.6m of thickness in the underground and air pipe and 0.3m of thickness in the sea pipe. With this configuration the heat losses are quite close to the optimum case. The purpose in the hydraulic study has been quantifying the start pressure in the new line to fulfil the energy demand in the worst point of the line. With 320kPa at the start of line, the pressure in the worst point is enough to fulfil the nowadays demand, 3MW, and in the future when this line will be enlarged and the demand increased to 20MW, the pressure at the start of the line to ensure the requested pressure of 250kPa in the worst point should reach more than 380kPa. Having such pressure is not recommended to avoid the pressure hammer and to build a new pumping station after the sea pipe is recommended.

<p>This licentiate thesis proposes and analyzes three carbon dioxide novel cycles, namely: the carbon dioxide transcritical power cycle, the carbon dioxide Brayton cycle and the carbon dioxide cooling and power combined cycle. Due to the different characteristics of each cycle, the three cycles are suitable for different applications. The CO₂ transcritical power cycle is suitable for harvesting energy from low-grade heat sources, near which a low temperature heat sink is accessible. The CO₂Brayton cycle is suitable for harvesting the energy from relatively high-grade heat sources when there is no low temperature heat sink available. The CO₂cooling and power combined cycle is suitable for applications, where both power and cooling are needed (e.g. automobile applications, in which the cycle can utilize the energy in the engine exhaust gasses to produce power and provide cooling/heating to the mobile compartment room at the same time).</p><p>Several models have been developed using the software known as Engineering Equation Solver (EES)¹for both cycle analysis and computer aided heat exchanger design. Different cycle working conditions have been simulated and different working parameters’ influence on the cycle performance has been explained. In addition, Refprop 7.0² is used for calculating the working fluid properties and the CFD tool Femlab has been employed to investigate the particular phenomena influencing the heat exchanger performance.</p>

<p>Following licentiate thesis is a summary of the advances made within the research project - Micro- and nano structured surfaces for enhanced boiling heat transfer – which is a collaboration effort between the Divi-sion of Applied Thermodynamics and Refrigeration and the Division of Materials Chemistry at the Royal Institute of Technology (KTH).</p><p>The main objectives with this research project has been to: <i>develop</i> <i>methods for producing highly efficient boiling surfaces with well defined</i> <i>micro- and nano-structured porous surfaces by the use of micro- a</i>nd <i>nano-manufacturing techniques</i>. This objective has been achieved and the result is a novel micro-porous surface structure comprising dendritically ordered nano-particles of cop-per. The structure was fabricated by a high-current-density electrode-position process, in which the evolution of hydrogen bubbles serve as a dynamic masking template to the growth of the dendritic copper struc-ture. Important variables were identified that affect the production of the structure and its features, such as surface orientation during electrode-position, pressure and temperature of electrolyte, and a final heat treat-ment of the surface under reduced atmosphere, all of which have previ-ously not been reported on.</p><p>Experimental tests have been conducted in a widely used refrigerant, R134a, where the micro-porous structure was shown to enhance the boiling performance of a copper surface over 15 times compared to a regular copper surface. The boiling characteristics of the structure were found to be dependent on controllable surface characteristics. The re-markably good boiling performance of the novel micro-porous en-hancement structure has been attributed to its high porosity ( ~94%), a dendritically formed and exceptionally large surface area, and to a high density of well suited vapor escape channels (>50 per mm2).</p><p>A patent application, intended to protect the enhancement structure and its fabrication method, was submitted to the Swedish patent authorities (PRV) on March 1st, 2006.</p>

<p>A method of exhaust heat recovery from a spark-ignition internal combustion engine was explored, utilizing a steam reforming thermochemical reactor to produce a hydrogen-rich effluent, which was then consumed in the engine. The effects of hydrogen in the combustion process have been studied extensively, and it has been shown that an extension of the lean stability limit is possible through hydrogen enrichment. The system efficiency and the extension of the operational range of an internal combustion engine were explored through the use of a methane fueled naturally aspirated single cylinder engine co-fueled with syngas produced with an on board methane steam reformer. It was demonstrated that an extension of the lean stability limit is possible using this system.