In recent years carbon dioxide (CO2, R-744)has moved to the foreground as an environmentally friendly alternative to commonly used CFCs and HFCs, which are being phased out due to its high ozone depleting and global warming potentials. R-744 is not only environmentally friendly but due to its unique properties, it is also ideally suited for the use in heat pump water heaters. High cycle efficiencies are achievable even at high hot water temperatures. The high cycle efficiency not only leads to energy and cost savings but also ties in with the drive for implementation of energy saving measures in South Africa. It is therefore paramount to continue development and implementation of R-744 in heat pump water heaters. Optimizing the cycle efficiency is only possible if detailed component simulation models, taking these unique properties of R-744 into account, are available. The purpose of this study therefore was to develop a detail simulation model of a concentric tube-in-tube water-to-refrigerant evaporator, as well as a fin-and-tube air-to-refrigerant evaporator model. Data from the North-West University R-744 heat pump test bench were used to verify the tube-in-tube evaporator simulation model. The discrepancies in the cooling capacity between the simulation and test bench can be attributed to the presence of lubricant in the system.The fin-and-tube model was verified by testing it against the NIST program EVAP-COND (NIST 2010). Overall there was good agreement between the results of the two programs, with EVAP-COND predicting a lower cooling capacity(6% to 14%) and and a higher pressure refrigerant pressure drop (30% to 50%). It was found that both the heat transfer correlation of Jung et al. (1989) and the pressure drop correlation of Choi et al. (1999) are able to predict the experimental values accurately and are valid for use in both the evaporator models developed. To demonstrate the use of the detail evaporator fin-and-tube model, an evaluation of the different tube geometries, commercially available in South Africa, for use with R-744 fin-and-tube evaporators was done. For a fin-and-tube evaporator it was found that the most cost effective option is to use ⅜" (10.05 mm)copper tubes and the least effective is " (12.6 mm) stainless steel tubes. / Thesis (MIng (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2013.

Heat driven adsorption cycles use heat sources ranging in temperature from 80 - 150 °C to provide cooling, and have been used in both air conditioning and refrigeration applications. Adsorbent heat pumps operate with low cost, simple components, and very little vibration, making them appealing as an alternative heat pump technology. However, they have been limited thus far to commercial and industrial scale applications. To date, adsorption systems have predominantly used natural or industrial waste streams as heat sources in the 10s of kW range. This work expands the scope of adsorption applications to include heat driven cooling at small capacities (watts) and mobile cooling without electronic controls. Autonomous heat driven adsorption system controls are proposed and tested for these systems. Component and system level models are developed for design and assessment. Major trends in system performance with scale are identified and the causes for these scaling effects are presented. New adsorbent bed designs are proposed and modeled for small-scale adsorption systems. The small-scale adsorbent bed designs are fabricated and tested. Models are validated and refined based on the experimental results. Through a combination of modeling and experimental results, this work demonstrates the feasibility of adsorption system application at capacities that two orders of magnitude lower than any previously demonstrated work.

Solar assisted single-stage absorption heat pump (AHP) was used to supply energy to a floor-heating system by using the exergy methods. An existing duplex-house,in Ankara, with a heating load of 25.5 kW was analysed. Heating loads of the spaces in the building were calculated and a floor heating panel was modelled for each space leading to the capacity of the AHP before it was designed. Solar energy was delivered to the evaporator and high temperature heat input delivered to the genarator are met by auxiliary units operating with natural gas.The solar energy gained by flat-plate collectors was circulated through AHP.The anaysis performed according to the storage tank temperature reference value if the water temperature leaving the storage tank exceeds a predetermined value it is directly circulated through the floor heating system. Exergue analysis were carried out with Mathcad program. Exergy analysis showed that irreversibility have an impact on absorption system performance.This study indicated which components in the system need to be improved thermally.A design procedure has been applied to a water-lithium-bromide absorption heat pump cycle and an optimisation procedure that consists of determinig the enthalpy, entropy ,exergy, temperature, mass flow rate in each component and coeficient of performance and exergetic coefficient of performance has been performed and tabulated.

A comprehensive study of a miniaturized thermally activated cooling system was conducted. This study represents the first work to conceptualize, design, fabricate and successfully test a thermally activated cooling system for mobile applications. Thermally activated systems have the ability to produce useful cooling from waste heat streams or directly from the combustion of liquid fuels. Numerous concepts of miniaturized or mobile, active cooling systems exist in the literature but up to this point, successful fabrication and testing has not been documented. During this study, a breadboard absorption heat pump system was fabricated from off the shelf or in-house, custom-built components. The breadboard system was used to validate the feasibility of operating an absorption heat pump with a cooling capacity of about 300 W. Subsequently, a flexible and scalable design methodology for designing miniaturized absorption heat pumps was developed. A miniaturized, 300 W nominal cooling capacity ammonia/water absorption heat pump cycle with overall dimensions of 200 × 200 × 34 mm and a mass of 7 kg was then fabricated and tested. Testing of the absorption heat pump was conducted over a range of heat sink temperatures (20 ≤ T ≤ 35°C) and desorber thermal input rates (500 ≤ Q ≤ 800 W). Evaporator coolant heat duties in the study ranged from 136 to 300 W, while system COPs ranged from 0.247 to 0.434. At a nominal rating condition of 35°C heat sink temperature, the maximum thermal input of 800 W produced a cooling effect of 230 W. This represents a cycle COP of 0.29. Analysis of the experimental data indicated that future work should focus on improved desorber and rectifier designs to improve refrigerant purity. It is estimated that a system similar to the one in this study, with all fluid connections made internal to the system, could achieve the same cooling capacity with a system mass of 2.5 - 3.5 kg in an envelop of 120 × 120 × 25 mm.

Thesis (Ph. D.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 177-192) Also available in print.

With the ever-growing energy demand that world is currently going through and the danger of climate change around the corner, wagering in renewable energy seems to be the right path to create a more smart and green future. Sweden has put great effort on decreasing its dependency on oil, in fact in 2012 more than 50 % of its electricity came from the renewable source and has a plan in making it 100 % in 2040. However, when it comes to heating systems Sweden depends greatly on district heating, and situations which buildings are located outside the district heating system’s reach is not uncommon, hence for those buildings, other options such as solar power or heat pumps are considered. Many buildings located in Skutskär suffer from the problem stated above. The particular building analyzed in this thesis uses electrical radiator and furnace as sources of heat, which implies high energy uses and financial expenses. For this reason technical and financial analysis of using each alternative system for a single family house located in Skutskär had been done. Using solar powered system is deemed to be quite ineffective, as Sweden has poor solar radiation. In order to compensate the poor sun hours during the winter, 51 photovoltaic (PV) panels or 19 solar thermal panels would be required. This high initial investment needs long period of time in order to be profitable, 15 years for solar thermal system and 21 years for solar PV system. On the other hand, the results from the heat pumps are quite satisfactory, the fastest payback period is around 4 years. This is achieved by using air source heat pump (ASHP), the annual saving in this case is three times higher than using solar photovoltaic panels, making the usage of ASHP more attractive than any solar energy system. However, when annual saving is concerned, the ground source heat pump (GSHP) system is capable of generating even higher saving, but the initial investment is significantly higher, extending the payback period to 6 years.

The present master thesis was done during the spring of 2018. A cottage located in Vifors is studied with regard to its heating requirements. At the time of the study, the house could not be inhabited the whole year because there was no tap hot water available and the space heating demand was covered by electricity. Thus, an alternative heating supply is required to be developed. As a strategic prerequisite, the solution should be achieved considering both solar thermal collectors and a heat pump.First, the characteristics of the building were collected/determined in order to obtain the total heating demand per month and hence annually. Parameters such as the U-values, roof orientation, room dimensions, ventilation rates and internal gains were required to configure the building model in the software IDA ICE 4.8. In addition, the amount of tap hot water required per year was determined as 17 m3 per year. Cold water at 5 °C had to be heated until 55 °C to obtain the tap hot water.Once the heating requirements were known, the most suitable solution was to use a combi system (solar thermal collectors and a heat pump). Solar energy could fulfil the demand in the summer and the heat pump provided energy in the winter. For a commercial model of the flat solar thermal collector (Vitosol 100-F) the solar system was sized according to the heating demand in the summer time. The maximum energy that could be obtained from the solar collectors in summer was calculated, the rest of the demand had to be fulfilled by a heat pump, model WPL-18 E.The achieved solution is compounded by the heat pump and 3 solar thermal collectors with a surface of 2.33 m2 each. The solar energy obtained is 1 843 kWh per year, which covers 9 % of the total annual heating demand (20 098 kWh). However, the 98 % of the heating demand during the summertime comes from the solar collectors. The investment cost is 113 900 SEK and the payback period is estimated in 8 years.

Since the building construction area is accounted for high share of energy usage (36 %) in Europe, there is high demand to pay attention to this area accurately. Sweden which is one of the pioneer countries in terms of building energy efficiency plans to reduce this value to 50 % by 2050. To reduce this value there is a need to define a mandatory guideline for builders by the government. So national board of housing, building and planning (Boverket) were given responsibility to define these regulations for builders and house owners. Parallel with that Swedish green building council developed a certification considering the buildin g’s energy demand, indoor air climate and environmental impact of building called Miljöbyggnad. While all the existing and new buildings following Boverket’s regulations meet this certification’s lowest limitations, some ambitious builders tend to fulfil its highest level of limitations called Gold level. This study aimed to design a house in the area of Smedjebacken to meet Miljö byggnad’s gold house’s energy category requirements. To meet the mentioned requirements several parametric studies regarding insulation thickness, windows assembly, heating and ventilation system are done via simulation software called TRNSYS. The result of testing several models show that although windows assembly does not affect this building ’s energy demand very much, other parameters such as insulation ’s thickness and type of heating system have a key role. In addition, a parametric study regarding the impact of thermal mass on the building energy demand is performed. The result shows that the effect of removed massive wood is compensated by replaced additional mineral wool insulation. In conclusion it is concluded that a single family house located in a cold climate like Smedjebacken using district heating cannot meet Miljöbyggnad’s gold level criteria without help of heat recovery ventilation. Furthermore, building with ground source heat pump as its heating system can meet Miljöbyggnad’s principals easier than those having district heating. In this case building with 200 mm insulation thickness even with exhaust air ventilation meets certification principals easily.

The goal of the diploma thesis was to elaborate applicable solutions for the use of low-potential waste heat from the Nuclear Power Plant Temelín for agricultural production. A greenhouse of the 1 hectare size has been proposed as a model project for tomatoes production. First, in diploma thesis discussed universally questions related with building greenhouse, such is safety issues servis Nuclear Power Plant, the suitability of use different technologies, property law, suitability of the locality construction and impact on the environment... Then was detailed processed version for heating-up greenhouse of the 1 hectare, including solution key problem . Part of this diploma thesis is economic balance and proposal for the future practical use.

Environmental issues are important challenges for today’s society. Lots of the energy used by humans comes from fossil energy sources resulting in the environmental threats. A considerable amount of this energy is used in the building sector. Industrial buildings and sports facilities are large users of energy and thus becomes very interesting in an optimization point of view. Modelling of the systems allows for cheap and effective optimizing of the energy usage and effectivity measures can be investigated and implemented. This study creates a model of the indoor ice rink arena of ABB arena syd in Västerås using TRNSYS as the main software for simulation. Focus is placed on the heating of the arena through heat pumps and district heating, and cooling of the ice in the arena using cooling machines. The effect of PV as well as a battery storage in the arena is also investigated as an effectiveness scenario. The results from the study revealed that it is possible to simulate the heating demand for the arena, accurately identifying the normal demand as well as the instances when the demand peaks and the magnitude of the peaks. It is also possible to simulate the cooling demand for the ice over extended time periods. However, this study could not identify the peaks for cooling demand. It is also beneficial for the system to install PV, but not a battery storage. With current price levels for electricity it is however not a very beneficial deal. With higher electricity prices the investment is preferable. The study also concludes that TRNSYS can be used for modelling an ice rink sports arena, however it leaves room for improvement on that aspect.