The world today has large challenges in order to manage a changing climate and the consequences that the climate change has on the environment and human living standards. This climate change is largely affected by the emissions of greenhouse gases, which come from usage of fossil fuels. This is a global problem that will affect the whole world and cause an increase of mean global temperature, which would lead to drastically changes in the living environment for human beings. A large part of the use of fossil fuels is connected to electric energy production. In EU almost half of the electric energy production is based on combustion of fossil fuels like natural gas and coal. These types of energy production need to be phased out and the energy consumption needs to decrease.   With climate change as a background there is a development towards more sustainable households. Companies around the world today invest in developing products that are more environmentally friendly. Household appliance companies develop products that use less water and energy, and a company like ASKO appliances AB tries to equip their machines with a new type of drying system. This new system would mean that less energy is needed for the drying cycle and humid air would not flow out in the kitchen.   The new drying system uses an air channel mounted on the side of a machine where moist hot air passes through the channel. During the passage the hot air will exchange heat with a cold surface inside of the channel. This work is focused on finding an optimal geometry of the air channel that enhances heat transfer between hot air and a cold surface. Installing obstacles inside of the duct could alter the flow pattern, and therefore enhance heat transfer. The work is mostly computer based with simulations performed in software called COMSOL Multiphysics. The software is used to build a 3-D model, where different geometries of obstacles are placed inside of the air channel. Results from simulations are compared with results from experimental trials, thus validating the computer model. Fluid flow simulations are used to investigate the effects of heat transfer for different types of geometries and sizes of obstacles. Parameters like influence angle and obstacle distance are tested.   The study shows results that obstacles inside of an air channel enhance heat transfer between a fluid and a surface. V-shaped obstacles perform the best results in order to enhance heat exchange, this compared with other tested geometries like W-shaped, wave-shaped obstacles and geometry without obstacles.   Different influence angle and distance between obstacles affects heat transfer, the study indicates that influence angle has larger effects on heat transfer than obstacle distance.

Although the issue of uncertainties in cost model parameters has been recognized as an important aspect of life-cycle cost analysis, it is often ignored or not well treated in cost estimating. A simulation approach employing kernel estimation techniques and their asymptotic properties in the development of the probability distribution functions (PDFs) of cost estimates is proposed. This eliminates the guess work inherent in current simulation based cost estimating procedures, reduces the amount of data sampled and makes it easier to specify the accuracy desired in the estimated distribution. Building energy costs can be reduced considerably if air duct systems are designed for the least life-cycle cost. The IPS-Method, a simple approach to HVAC air duct design is suggested. The Diameter and Enhanced Friction Charts are also developed. These are charts that implicitly incorporate the LCC and are better than the existing Friction Chart for the selection of duct sizes. Through illustrative examples, the ease and effectiveness of these are demonstrated. For more complex designs, a Segregated Genetic Algorithm (SGA) is recommend. A sample problem with variable time-of-day operating conditions and utility rates is used to illustrate its capabilities. The results are compared to those obtained using weighted average flow rates and utility rates to show the life-cycle cost savings possible by using this approach. Although life-cycle cost savings may be only between 0.4% and 8.3% for some simple designs, much larger savings may occur with more complex designs and operating constraints. The SGA is combined with probabilistic cost estimating to optimize HVAC air duct systems with uncertainties in the model parameters. The designs based on the SGA method tended to be less sensitive to typical variations in the component physical parameters and, therefore, are expected to result in lower balancing and operating costs.

The mein objective of this diploma thesis is to optimize the oil cooler of the VUT 100 aircraft, so that it complies with the CS-23 regulation and requirements of the engine producer. This is fulfilled by using of suitable oil cooler and by optimization of the air duct. Computational Fluid Dynamics approach – namely Ansys Fluent software package is used for it.

My diploma thesis focuses on design of air-conditioning system for chicken breeding spaces. In the background are considered general issues of air-conditioning, hatchery layout and microclimate for eggs incubation and chicken breeding. The research part is divided into two parts – Calculations and Design. The Calculations address the amount of incoming fresh air, heat loss, heat load and psychrometric calculations for summer and winter periods. The Design focuses on defining suitable diffusers and air-ducts, optimal air-conditioning unit with fans corresponding to hatchery requirements and pressure loss in ducts. The technical drawings and a list of used material are included.

The diploma thesis deals with design of warm air heating and ventilating system for low energy house. Introduction of this thesis is focused on dividing residential buildings by their heat requirement. Then problems of residential building ventilation and possibilities of warm air heating systems including heat recovery are presented. In the next chapter summary of ventilating units with heat recovery and warm air heating units for residential low energy buildings and pasive family houses is presented. Calculation of low energy house heat losses, which is solved, is based on CSN 06 0210, CSN 73 0540 and CSN EN 12831 standards. Design and calculation of warm air heating and ventilation system and ground heat exchangers is also described. Floor heating system, fireplace insert and solar heating system are designed as supplementary systems. At the end of this thesis the control system is presented. Project documentation is enclosed in appendix.