Solar energy constitutes one of the main alternatives for facing the energy problems of the future, taking into account the foreseeable depletion of the fossil fuels. Transpired solar air collectors are relatively simple alternatives, which do not need a continuous supervision and are mostly maintenance free. Their life cycle is relatively high, around 25 years, and the total investment can be fully recovered in the short-term. The aim of this master’s thesis is to analyze the feasibility of installing transpired solar air collectors as secondary systems in big industrial buildings, for heating purposes. The collectors would be designed for compensating the heat losses of a building which is mainly heated up by a heat pump system. Precisely, this work tries to evaluate the profitability of installing these collectors in Gävle, taking into account the particularities of this location in the considered study. This project work is focused on testing if these systems can provide enough thermal energy for heating up big-sized industrial buildings. For this purpose, firstly, the heat demand of the building for each month was calculated; secondly, the maximum output from the collector was estimated, using WINSUN simulator; and, finally, the energy difference that had to be covered by the main system was calculated. Once this was done, the yearly running cost for the main system and the total investment for the transpired air solar collector were estimated. Due to the lack of experimental data, the obtained results can only be taken as approximations. All the calculations and estimations have been made using WINSUN, a simulator that has been configured according to the particularities of the project. The results show that the solar collector provides a total thermal output of 29.700 kWh/year (system which has a total investment of 77.000 SEK). The total heat demand of the building is estimated to be of 87.100 kWh/year, being 51.800 kWh/year fulfilled by the heat pump system (which has a yearly running cost of 24.000 SEK/year). The collector has an average efficiency of 51,04%.

This thesis focuses on design of device to generate hot air. This generator is supposed to be used to perform thermal tests for a company. Introduction summarizes general knowledge about ventilators, heat transport in air flow, and pressure losses. Main part of the thesis describes development of the generator. Initial design was followed by selection of suitable solution variants, design of major parts of the generator supported by calculations and overall conception of the generator. Final part summarizes the achievements and economic analysis.

This thesis presents an optimisation approach and techno-economic evaluation tool for a system consisting of a transpired solar air collector and air source heat pump in a series arrangement. The thesis also investigates the application of the developed tool for feasibility study of a solar heat pump system for a group of three multi-family houses located in Ludvika, Sweden.   Transpired solar air collector is used in combination with an air source heat pump to meet space heating and hot water demand for the defined location. Moreover, the solar pre-heated fresh air is used as a heat source for the heat pump evaporator to improve its coefficient of performance. Solar heat pump systems are extensively studied by numerous researchers, However the analyses about techno-economic feasibility of air source heat pump with transpired air solar collector are still lacking. Therefore, an optimisation tool is developed based on the non-linear programming for coherent operation strategy and variation in collector flow rate. The effect of optimisation along with the techno-economic feasibility for a demo case residential building in Sweden is then preliminary studied based on the defined boundary conditions.   The analysis is gradually progressed through several phases of thesis starting from system description and followed by tool methodology and case study. A pre-developed dynamic simulation model is used to obtain the space heating and domestic hot water demand of the building. The electricity expenses of the existing system are evaluated and the results are used as a reference to compare the savings resulting from the installation of transpired solar collectors with gross area of 50 m2.   The results are presented as a defined economic indicator such as payback period. The results of the simulation reflect that the installation of 50 m2solar collector area leads to 3 % savings compared to the defined reference case, with a simple payback of 22 years. Moreover, results also indicate that variation of collector flow rate and operation timings are effective strategies to maximise the system savings. The analysis reveals that the optimisation can result in up to 60 % additional savings in comparison to a fixed flow rate case.   The developed tool has a potential use for feasibility check at an earlier stage of the installation project, without the need for extensive system simulations. Moreover, the tool overcomes the shortcoming of various available tools such as RETscreen solar air heating project model, which are not designed to evaluate the performance of solar collectors with heat pump systems.

The influence of uniformity of heat transfer with respect to the effect of heat treatment was investigated by correlating engineering parameters with the quantified heat treatment effects. Differences in treatment effect in terms of quality, anti-pathogen and chilling injury (CI) control properties among commodities was studied by exposing them to different target temperatures. Similar effects were also evaluated and quantified within an individual commodity by a custom-designed device. This device, whose design parameters were based on a heat transfer simulation, insured that one hemisphere of a tomato was exposed to air at 39°C and 0.24 m s-1; while the other hemisphere was exposed to air at a lower temperature with a velocity of0.24 m s-1 or 0.12 m s-1. / Single-temperature heat treatment was most effective in limiting pathogen development and varied according to the parameter measured: 38°C for hypersensitive response (HR), 36°C for tissue breakdown, 36°C, 38°C or 39°C for mycelium abundance, and 38°C or 39°C for lesion size. Bilateral differences in temperature across the fruit significantly affected disease control: decreasing temperature differences significantly improved the uniformity of disease control. / Some of the effects of heat treatment on tomato quality, such as color development and resistance to CI, appear to be localized. A significant difference in redness was identified between heated parts and unheated parts of tomato fruits immediately after treatment; and the differences persisted during storage. Differences in lightness and chroma were noted on day 4. Delay in ripening caused by heat treatment was confirmed through the higher TA and TSS values of heated tomatoes or heated portion of partially heated tomatoes. / The heated parts of tomatoes showed a stronger resistance to chilling injury. The effective temperature control range for CI was wide, but temperatures higher than 39.5°C for 23 h hot air treatment could lead to adverse effects. / Differences in physiological effects between hemispheres in two chambers was reduced by directly decreasing the temperature difference between upper and lower chambers or relatively increasing the heating air flow rate, highlighting the importance of improving the uniformity of air flow around each individual treated fruit.

Thesis (M. Sc. (Agriculture)) --University of Limpopo, 2017 / Tea is one of the most popular consumed beverages in the world, which has beneficial properties such as anti-oxidization, anti-carcinoma and preventing arteriosclerosis. The major essential components of catechins present in tea leaves, includes epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG), epicatechin (EC), gallocatechin (GC) and catechin (C). Influence of time-based hot air drying method on chemical composition of the Jatropha zeyheri Sond, widely consumed in rural communities of Zebediela (Khureng village), Limpopo Province, South Africa, was investigated. Four treatments, namely; 0, 24, 48, and 72 hours, were arranged in completely randomised design (CRD), replicated five times. The study demonstrated that drying significantly increased total phenolic content, total antioxidant capacity and tannin content. It also demonstrated that drying significantly increased minerals elements; Mg, K, P, S, Al, Co, Mn, Si and Zn content and decreased Na, Ca and Ni and Zn quantities. Sodium-potassium ratio was very low across drying periods. Drying time did not significantly influence proximate chemicals; energy, protein, carbohydrates, ash and fibre content. Moisture and fat were significantly increased by drying period. Results of the study suggested that time-based hot air drying method improved the chemical composition of J. zeyheri, which has the potential of enhancing nutrition in marginal rural communities of Limpopo Province.

The task of this master´s thesis is an evaluation of warm-air heating system in a low energy family house from the viewpoint of thermal comfort during winter season. The CFD simulation using CCM+ code was used for this purpose. The environment parameters in the central living room were evaluated for two variants – with underfloor heating and without it. The thermal comfort was evaluated using indices according ČSN EN ISO 7730 standard.

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Unblanced forced-air heating systems create a situation that may be detrimental to the building envelope. These systems create an air pressure differential, which acts as a moisture transport mechanism, which has the potential to carry moisture, through the smallest of openings in the building envelope. Once this warm air enters the wall cavity it comes into contact with the unheated surfaces of the components making up the building envelope, which are below dew point during the heating months. As this moisture-laden air reaches its dew point, condensation occurs. / Department of Architecture

Main purpose of project is design of economical ventilation system. Designed preasure equal air heating system is supportet by sollar collectors and fluid-ground heat exchanger.

Indoor climate of industrial halls is now advantageously shaped radiant heating systems, which are more flexible and efficient than convection systems. The crucial component of indoor climate in these systems mean radiant temperature. The work focuses on theoretical and experimental research on the location and operation of radiant panels. For the theoretical part is used new computer software able to calculate the Institute TZB mean radiation temperature distribution in 2D space. The experimental part was carried out comprehensive measurements of indoor climate parameters specific industrial halls and subsequently compared. Work includes the design and comparison of three variants of heating in the indoor facility.