This thesis conforms conventional and advanced experimental techniques for the measurement of and mathematical prediction of velocity pressure-loss factors (k-factors) for fittings used in heating, ventilation and air-conditioning (HVAC) systems. After an extensive study of different tracer-gas experimental techniques, the constant injection method is applied to various duct fittings on a small scale HVAC system situated in a laboratory. The results are compared with those of experiments performed using a more conventional technique using a Pitot-static tube. The basis of the experimental procedure is to achieve an accurate method of measuring the mean air velocity within a duct. This allows an accurate estimate of the velocity pressure-lossf actor to be obtained. A wide variety of duct fittings are investigated experimentally and numerically including bends, transitions, branches, inlets, outlets and obstructions such as orifice plates, wire mesh and lateral pipe obstructions. Computational fluid dynamics (CFD) is applied to each duct fitting tested in the lab. A commercially available package FLUENT is used with a high powered computer to simulate the airflow through various duct fittings. The pressure loss and velocity vectors are predicted for each particular duct fitting and therefore a prediction for k-factors is obtained. k-factor predictions are compared with experimental results and published data given in ASHRAE and CIBSE guides in order to assess the accuracy of CFD prediction. It is shown that as an accurate method for prediction of k-factors in duct fittings, CFD is a useful tool for the design and development of HVAC systems. The application of CFD allows the designer to vary any duct component with ease to observe the effect on a particular duct fitting without incurring the expense of laboratory experimentation. It is also shown that values of current published kfactors are greatly over estimated leading to oversizing of HVAC system fans. Experimentally produced k-factors obtained using the tracer-gas method and CFD predictions are approximately 20% lower than current data available to HVAC system designers. CFD may be applied to various applications in the field of heat-pumps and refrigeration systems. A detailed investigation is carried out here to compare CFD prediction and experimental results of several low pressure and high pressure ejectors commonly found in refrigerator absorption cycles. The compressible flow of refrigerants was modelled through an ejector to obtain a prediction of the entrainment ratio ( i. e. the ejector's ability to entrain a refrigerant from an evaporator using a hot main flow through a nozzle). These predictions were then compared with experimental results and this indicated that CFD could serve as a useful tool in the design of refrigeration systems. Application of CFD has also been studied in relation to the investigation of pressure loss through different types of evaporator/condensecr oils found in heat pump systems; here the design of such coils is important to the operating efficiency. The pressure loss across heat-pipes found in ducted flows is also predicted using CFD; in this case the geometry and the thermal conditions play an important role in the overall pressure loss.

Thesis (M.S.)--Rochester Institute of Technology, 1990. / Typescript. References: leaf 324.

Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2002. / Includes bibliographical references (leaves 61-63). Also available in electronic version. Access restricted to campus users.

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2006. / Title from title screen (site viewed June 11, 2007). PDF text: x, 153 p. : ill. UMI publication number: AAT 3243742. Includes bibliographical references. Also available in microfilm and microfiche formats.

This thesis presents a new method developed to adapt existing hydronic systems in buildings to take advantage of low temperature district heating (LTDH). The work carried out was performed by extensive use of buildings’ energy modelling, validated through recorded data. Two different case studies were investigated and the dynamic heat demand profiles, simulated for each building, were used to evaluate plate radiators connected to single and double string heating loops. The method considered an optimisation procedure, based on supply and return temperatures, to obtain the required logarithmic mean temperature difference (LMTD). The results of the analysis are presented as the average reduction of LMTD over the heating season compared to the base case design conditions. The developed strategy was applied to a Danish single family house from the 1930s. Firstly it was hypothesised a heating system based on double string loop. Two scenarios were investigated based on the assumption of a likely cost reduction in the end users energy bills of 1% per each 1◦C reduction of return and average supply and return temperatures. The results showed possible discounts of 14% and 16% respectively, due to more efficient operation of the radiators. For the case of single loop system, the investigated scenario assumed a cost reduction in the end users energy bill of 1% per each 1◦C lower reduction of average supply and return temperature. Although low return temperatures could not be achieved, the implementation of the method illustrates how to efficiently operate these systems and for the given scenario a possible discount of 5% was quantified. The method was also applied to a UK small scale district heating (DH) network. The analysis began by assessing the buildings of the Estate having double string plate radiator systems. Assuming a likely cost reduction in the end users energy bills of 1% per each 1◦C reduction of return temperature, the optimisation led to obtain a possible discount in the end users energy bills of 14% with a possible yearly average return temperature of 41◦C, compared to the present 55◦C. Moreover, few improvements in the operation of the heat network were proposed. It was assumed to operate the buildings with underfloor heating systems (UFH) with average supply and return temperatures of 40/30◦C, whereas the ones with plate radiators with the optimised temperatures of 81/41◦C. The results shown that an overall average return temperature of 35.6◦C can be achieved operating the heat network as suggested. This corresponds to a decrease in the average return temperature of 18.6◦C compared to the present condition and to a reduction of 10% in the distribution heat losses. Finally, the lower average return temperature achievable would guarantee a better condensation of the flue gases, improving the overall efficiency of the biomass boiler. This was quantified as a possible reduction of fuel consumption of 9% compared to present conditions.

This research explores technological interventions to reduce energy use in the domestic sector, a notable contributor to the global energy footprint. In the UK elevated challenges associated with renovating an outdated, poorly performing housing stock render a search for alternatives to provide immediate energy saving at low cost. To solve this problem, this thesis takes a holistic design approach to designing and implementing a spatiotemporal heating solution, and aims to investigate experiences of comfort, thermal comfort concepts for automated home heating, users’ interactions and experiences of living with such a system in context, and the underlying utility of quasi-autonomous spatiotemporal home heating. The mixed-methods research process was employed to explore and answer four questions: 1) what is the context within which these home heating interfaces are used, 2) to what extent can spatiotemporal automated heating minimise energy use while providing thermal comfort, 3) how are different heating strategies experienced by users, and 4) How do visibility of feedback, and intelligibility affect the user experience related to understanding and control? Ideation techniques were used to explore the context within which the designs are used with regard to all factors and actors in play and resulted in a conceptual model of the context to be used as a UX design brief. This developed model used mismatches between users’ expectations and reality to indicate potential thermal comfort behaviour actions and mapped the factors within the home context that affected these mismatches. Potential user inclusion through participatory design provided stakeholder insight and interface designs concepts to be developed into prototypes. The results of a prototype probe study using these prototypes showed that intelligibility should not be an interface design goal in itself, but rather fit in with broader UX design agenda regarding data levels, context specificity, and timescales. Increased autonomy in the system was shown not to directly diminish the experience of control, but rather, control or the lack of originated from an alignment of expectations and reality. A quasi-autonomous spatiotemporal heating system design (including a novel heating control algorithm) was coupled with the design of a smartphone interface and the resultant system was deployed in a low-technology solution demonstrating the potential for academic studies to explore such automated systems in-situ in the intended environment over a long period of time. Assessment of the novel control algorithm in an emulated environment demonstrated its fitness for purpose in reducing the amount of energy required to provide adequate levels of thermal comfort (by a factor of seven compared with EnergyStar recommended settings for programmable thermostats), and that these savings can be increased by including occupants’ thermal preference as a variable in the control algorithm. Field deployment of that algorithm in a low-tech sensor-based heating system assessed the user experience of the automated heating system and its mobile application-based control interface, as well as demonstrated the user thermal comfort experience of two different heating strategies. The results highlighted the potential to utilise the lower energy-use “minimise discomfort” strategy without compromising user thermal comfort in comparison to a “maximise comfort” strategy. Diverse heating system use behaviours were also identified and conceptualised alongside users’ experiences in line with the developed conceptual model. A rich picture analysis of all previous findings was utilised to provide a model of the design space for home automated heating systems, and was used to draw interface design guidelines for a broader range of home automation control interfaces. The work presented here served as important first steps in demonstrating the importance of assessing UX of automated home heating systems in situ over elongated periods of time. Novel contributions of (i) conceptual model of automated systems’ domestic context and thermal comfort behaviours within, (ii) nudging this behaviour by selecting a “minimise discomfort” heating strategy over “maximise comfort”, (iii) using UX to influence user expectations and subsequently energy behaviour, and (iv) inclusion of thermal preference in domestic heating control algorithm were all resultant of examining naturally occurring behaviours in their natural setting. As such, they are important exploratory discoveries and require replication, but provide new research directions that would allow reduction of domestic energy use without compromise.

Worldwide energy demand in buildings represents about 40-50% of the total energy consumption. In hot climates, such as Middle East and North Africa (MENA) countries, about 30% of the national power demand is used for HVAC applications in buildings. This has led to escalation in power demand in buildings for indoor air-cooling and high energy bills. This is exacerbated further by the widespread adoption of energy intensive and commercially dominant vapour compression air conditioning systems as the technology of choice. This research aims to address the potential of novel designs of evaporative cooling systems for space cooling and thermal comfort in buildings with reduced water and energy consumption, and low environmental impact as an alternative to vapour compression where climatically is suitable. High water consumption rates and low cooling effectiveness are some of the issues affecting the performance of existing Indirect Evaporative Coolers (IEC). A new configuration of IEC combining heat pipe heat exchanger and porous ceramic tubes is investigated in this work. The proposed cooler configuration is based on the concept of regenerative IEC system, this system incorporates heat pipes as passive heat transfer elements and porous ceramic tubes as wet medium mounted on the condenser side of the exchanger. The design of the cooler was carried out with consideration for size of the airflows channels, heat pipes for heat transfer, and porous ceramic tubes properties for water evaporation. A mathematical formulation of heat and mass transfer equations was used to develop a computer model to design and optimise the cooling system. Furthermore, a test rig was built to test a laboratory scale cooling unit, evaluate the performance and validate the simulation. The simulation results reveal that the Wet-bulb (WB) effectiveness of the cooler ranged from 0.524 to 1.053, the COP ranged from 6.33 to 17.01, and water consumption rates of the cooler were around 0.875-1.55 (l/kWh) of cooling capacity. Whereas, the experimental performance parameters of the cooler show the WB effectiveness was in the range of 0.422-0.908 for all test conditions, the COP was 4.62-13.16, and water consumption rates varied 0.841-2.82 (l/kWh) of cooling capacity. A good agreement was obtained between the experiments data and numerical results, the maximum errors between measured and computed results was around 3.94% and 4.51% of supply air temperature and humidity, respectively, while the discrepancy was in the range of 8.67-12.90% of the WB effectiveness. The impact of operational and design parameters on the cooler performance was evaluated in a parametric study using the developed numerical model. It was found that increasing the inlet air temperature, decreasing the inlet air flow rate, and/or increasing the working-to-inlet air flow ratio, results in improving the effectiveness and supply air temperature. Whereas, increasing the inlet air wet-bulb temperature depression, increasing the inlet air flow rate, and/or minimising the working-to-inlet air flow ratio leads to enhancing the cooling output and COP of the cooler. Additionally, increasing the thickness and/or the radius of ceramic tube causes a decline of cooler thermal performance. Therefore, it is recommended to operate the cooler at inlet air velocity of 2-2.5 m⁄s, 50% flow ratio of working-to-inlet air, and inlet air relative humidity below 35% for best results of supply air temperature, WB effectiveness, and COP. Whereas, for desert climate conditions, it is recommended to increase the number of heat pipe rows to 20 to insure sufficient cooling effectivity and performance that meet comfort levels. Finally, a brief economic assessment of the cooler annual operational performance for a case study was carried out, this IEC system provide sufficient cooling effectiveness to the conditioned space with significantly low power consumption compared to traditional air conditioner with annual saving of 77.60% of operational costs, and also substantially contribute to minimise CO2 emissions by saving about 86% of electricity consumption.

An examination of contemporary office buildings in the warm humid region of Kenya revealed the predominance of highly glazed lightweight buildings that are prone to overheating and rely on costly and unsustainable active climate control systems. In the midst of growing energy demand and a potential deficit in supply, the influx of these poorly designed buildings has intensified the need to explore viable climate-responsive design alternatives suitable to local conditions that can extend occupant comfort and reduce the need for energy intensive environmental control systems. This view is shared by the Kenyan government which has set ambitious targets to develop and enforce national codes for energy efficiency and conservation in buildings by 2030. However, despite the clear and urgent need, research shows that little work has been developed to date that can be applied to the Kenyan context and climate. In this research, ways of improving the thermal comfort and performance of office buildings in the warm humid city of Mombasa (latitude 4°S) were explored. The work was developed through a series of field studies of local vernacular and modern case study buildings and subsequent computer simulations. From this, vernacular Swahili-inspired design strategies were derived and the application of the potentially most significant mitigation strategy to typical local office buildings examined further. Although other work exists elsewhere that may be comparable to parts of this study, this is the first effort that brings together the post occupancy evaluation of buildings in Mombasa, a thorough investigation of the effectiveness of the vernacular strategies found in Swahili architecture, and the validation of the application of these strategies to modern offices. Initial findings derived from a parametric study revealed external shading to be the most effective design strategy as it alleviated solar heat gain transmitted through glazing into buildings, resulting in a significant reduction in discomfort hours. Subsequently, using a series of dynamic computer simulations run for a typical office building in Mombasa, the average monthly solar heat gain coefficient (SHGC) values were derived for a typical year. These previously unavailable latitude (and hemisphere) specific solar path indices were deemed critical in the provision of essential data for effective external shading device design. The findings indicated that low SHGC values of under 0.5 gave the general indication of low percentage of discomfort hours (under 10%). Additionally, estimates of potential annual cooling energy savings of up to 60% were made based on the reduction of SHGC values for shading elements of practicable size. The application of these study findings to two local office buildings revealed that the derived SHGC values and energy estimates provide useful references when considered for similar type office buildings on similar latitudes. For both buildings, it was predicted that energy savings of 15% to 61% could be achieved from the application of suitably sized external shading devices. It was suggested that this type of information would encourage designers to use external shading devices as a method of maintaining thermal comfort, conserving energy and lowering operating costs in office buildings. Finally, recommendations for the incorporation of minimum shading standards in building regulations have been made and presented in a design guidance document.

In 2009 the Brazilian government committed to support the construction of nearly 24 million new dwellings by 2022 through its housing programme Minha Casa, Minha Vida (My House, My Life). The initiative aims to tackle the housing shortfall of 5.546 million residential units and the 10.948 million units that are considered inadequate dwellings with poor living conditions. The potential economic, social and environmental impact of such large initiative is vast and consequently it is essential that the new dwellings are planned, designed and built to meet high levels of energy efficiency and thermal comfort. The ‘Fabric First’ is widely recognised as a design approach with great potential to deliver energy efficient and comfortable housing in a variety of different climates. Its principles have already been successfully incorporated in many buildings across European countries and elsewhere. Despite its success, research to date shows that the application of this approach has not been explored yet in the Brazilian context. In this work, ways of improving the thermal comfort and performance of Brazilian mass housing in three cities in southern Brazil (Curitiba, São Paulo and Porto Alegre) through the Fabric First principles were explored. The research was developed through sensitivity analyses of key envelope parameters and case studies. The sensitivity analysis was carried out in order to identify the best performance and the most cost-effective building envelope combination, using a simplified affordable Brazilian housing typology model that had its properties varied. A case study based on a generic representative model and a real optimised case study of typical 1-floor 2-bedroom mass housing typology were evaluated through computational thermal simulations and monitored data. The results of the sensitivity analyses were then used to inform the case studies performance analyses, developed in parallel to a cost analysis. Key findings from this study revealed that typical Brazilian building envelopes underperformed by up to 65% compared to super-insulated envelopes in terms of thermal comfort. In the real case studied this could represent up to 75% less thermal comfort. However, the additional costs of a super-insulated envelope showed to be 56-66% higher than the typical Brazilian envelope, with a payback period nearing the lifespan of the houses. In addition, it has been shown that relatively small improvements in the current building envelope could impact the upfront costs by only 6-12% but result in comfort improvement of about 45% against typical levels. These small improvements appear to be more suited to the cultural and economic Brazilian context and therefore are recommended as the best way forward.

The objective of my thesis was to suggest and size the equipment for a hotel kitchen air-conditioning according to the given parameters. This thesis deals with the calculation of the amount of circulating air, heat loss and profit and the psychometric calculation for summer and winter operation. It also contains the design of air channels, terminal components, air-conditioning unit and ventilation of machine room. Furthermore, it comprises of the suggestion of measurement system and regulation, estimation of energy demand, technical report and list of material items. The calculation is equipped with drawing documentation.