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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Applying user-centred design to the service of installing renewable heating technology into UK social housing properties

Moore, Natalie J. January 2014 (has links)
Global climate change and energy use have gained significance as principal issues in Government policy, with energy and carbon reduction targets becoming increasingly ambitious. The European Union have committed to a 20% reduction in both energy use and greenhouse gas emissions and for 20% of total energy supply to come from renewable sources by 2020, compared to 1990 levels. The UK has committed to a 34% cut in energy use within the same timeframe. The domestic sector accounts for over a quarter of all UK CO2 emissions and therefore poses an important area to address against the set targets. An overall stringent target has been set to reduce carbon emissions by 80%, against 1990 levels, by 2050 and it has been established that over two-thirds of the housing stock that will exist in 2050 is already built. Consequently, reducing household energy consumption and carbon emissions through retrofit measures is crucial. This doctoral research was carried out as part of a 3-year, interdisciplinary project Carbon, Control and Comfort (CCC) [EP/G000395/1]. The aim of the CCC project was to assist social housing tenants in reducing their energy use and carbon emissions associated with heating practices whilst maintaining comfort in the home. Technologies utilising renewable energy are progressively being introduced into social housing, particularly for the provision of heating and hot water. In order to meet carbon reduction targets, the uptake and installation of renewable technology needs to be successful and occupants must be able to use the technology effectively. This research investigated the service of installing heat pumps into social housing properties, from both the landlord s experiences and tenant s experiences, with particular emphasis on the implications for older tenants, a key group of users. It aimed to develop an understanding of the service delivery from the tenants interactions with the landlord and the heating system, sought to identify any need for improvement of this experience and propose measures to address these issues. Adopting a user-centred design approach, this research was conducted over three main phases comprising three empirical studies. A first exploration study investigated the current situation of heat pump installations in UK social housing and the experiences of both landlords and tenants during this process. Through this understanding, the needs and wants of both landlords, as the service provider, and tenants, as the service recipient, were identified and potential areas that could be addressed to improve the service emerged. Key requirements for improved information, particularly relating to the introduction of the technology and its control, were identified from reviewing current service delivery processes. A second study was carried out with stakeholders on both sides of the service, as a continuation of the user-centred design approach, to develop user requirements and ascertain the ways in which these key areas could be addressed. A set of recommendations was formed for the identified measures to improve the service. A particular key measure was prototyped, based on the requirements extracted from the first exploration study and further developed in the second study. This enabled an evaluation to be carried out through a third study, with end users assessing the prototype. This applied the final stage of the user-centred design process to the key touchpoint of the service delivery focused on as a result of the research, prior to implementation or further work. As a final part of this thesis, the author reflected on the research undertaken against the aim and objectives set out at the beginning of the thesis. The discussion of the research at the end of the thesis indicated where contributions to knowledge lie. Firstly, this is evident in the greater understanding of heat pump installations in UK social housing this research provides an insight into and what may improve this service. The resultant recommendations for improvements to the service delivery provide a new contribution to the area. Secondly, applying user-centred design to the service delivery of installing heat pumps into social housing is a new way of approaching the design of this service process. In a relatively immature area of industry, installations to date have been heavily focused on the technical aspects of the system and so this research provides a valuable insight into the human aspects of the service delivery.
2

Development of shape stable phase change materials with improved thermophysical properties

Mu, Mulan January 2014 (has links)
Shape stable phase change materials (SSPCMs) based on paraffin wax (PW) and high density polyethylene (HDPE) can be used as energy storage materials for utilization of renewable energy in buildings. An SSPCM could be formed by selecting a suitable wax in terms of melting temperature (T m) and a HDPE in terms of viscosity. However, the impact of waxes with different T m and HDPEs with different viscosities on the manufacture of SSPCMs and their thermo-physical properties has not been studied thoroughly. Therefore, the aim of the research reported in this thesis is to understand the effect of different waxes and HDPEs on the processing of SSPCMs typically used in buildings and the quantification of their thermal and mechanical propelties. SSPCMs based on a higher (H-PW, Tm = 56-58°C) and a lower (L-PW, Tm = 18-23 0c) Tm wax with a higher (hv-HDPE, MFI = 0.18) and a lower (lv-HDPE, MFI = 25) melt viscosity HDPE were prepared by an extrusion method and their thermal and mechanical properties investigated. The effect of addition of thermally conducting multi-walled carbon nanotubes (MWCNTs) to enhance thermal conductivity and other properties of these SSPCMs was also studied. Such understanding would thus help to assess and inform the design of SSPCMs as wall panels suitable for domestic applications.
3

Design and characterisation of fluidised bed cooling towers

Mbua Egbe, Louis January 2001 (has links)
This thesis discusses the operating characteristics and design of fluidised bed cooling towers (FBCT), which may be used to cool hot water for industrial purposes. Limited data exist for such a three-phase fluidised bed acting as a cooling tower. This motivated some early workers to investigate its usefulness in cooling tower applications and they showed that the FBCT produces heat and mass transfer rates much higher than in conventional fixed-bed towers. Despite this advantage, the FBCT has not been commercially exploited to date. An extensive experimental study is presented using up-to-date instrumentation to determine the thermal and hydraulic characteristics with a view to establishing a design criteria for full-scale FBCTs. Experimental tests were performed to account for the effect of the plenum chamber and the spray zone region upon the thermal performance of the FBCT. Data analysis was performed so that the effect of the fluidised bed alone as well as the plenum chamber could be known. A prototype was designed and built incorporating nine calibrated Platinum Resistance Thermometers for fluid temperature measurements with one located just below the fluidized bed itself while another was positioned below the plenum chamber to measure outlet water temperatures. Two differential pressure transducers and an electronic water flowmeter were used to measure air pressures and water flow rates respectively. All instruments were connected to a data-logger linked to a personal computer. Two different software packages were written and installed on the computer, to automatically retrieve experimental data from the rig during test runs and to automatically process the retrieved variables for analysis. Nine independent variables were measured in order to determine the tower thermal-hydraulic performance. Water and air flow rates ranged from 0.5 - 5 and 0.5 - 4 kg/s m2 respectively giving liquid/gas mass flux ratios that ranged from about 0.1 - 6. The inlet hot water temperature ranged from about 25 - 55°C while the inlet air wet-bulb temperature averaged about 18°C. Four different spherical packing arrangements were studied at static bed heights that ranged from about 25 to 400 mm. The spray nozzle height from the distributor grid ranged from 400 - 1500 mm. Data analysis was performed for thermal-hydraulic performance using both dimensional analysis and the Merkel approach. A least-square multiple regression analysis carried out on dimensionless and dimensional groups that resulted from this analysis showed that correlations derived are in good agreement with other experimental data. Correlations were derived for the prediction of the bed air pressure drop and hence the power requirement, the tower thermal performance, the minimum fluidisation velocity, and the expanded bed height. Correlations used to design a full-scale FBCT are presented. Novel work included measurements of local radial and axial temperature variations within the fluidised bed. Thermal performance decreased as the liquid/gas mass flux ratio was increased while it increased as the particle size was decreased. High density particles gave a higher bed air pressure, and hence a higher power requirement than low density ones. Minimum fluidization gas velocity was independent of the static bed height. Expanded bed height increased as the liquid and gas mass fluxes were increased. Thermal performance was found to increase when the effect of the plenum chamber was included in the analysis as compared to the fluidised bed itself. Methodological criteria for the design of a full scale FBCT have been developed. Design analysis suggests that FBCTs can be several times smaller in size than conventional cooling towers, and that they may operate with a similar or lower power requirement than the latter.
4

Thermal operating practice in mixed-mode buildings : higher education case study in a hot-humid climate

Mongkolsawat, D. January 2013 (has links)
The rapidly increasing demand for cooling in buildings and the growing evidence of ‘air-conditioning addiction’ concern energy policy makers in hot-humid countries. Despite this concern, many existing mixed-mode non-residential buildings in hot-humid climates are operated as fully air-conditioned. This research applies adaptive thermal comfort theory to address the potential reasons for this design-use mismatch and evaluate how to optimise the use of fan assisted natural ventilation in existing mixed-mode non-residential buildings in hot-humid countries in order to limit impending global climate change, focusing on the interrelationships between: individual thermal adaptability, organisational thermal adaptability and the role of facilities managers, pro-environmental attitudes, and user performance. This thesis hypothesises that Acceptance of fan assisted natural ventilation in existing mixed-mode non-residential buildings in hot-humid climates is affected by users’ perceived behavioural adaptive opportunities and psycho-physiological adaptation, as well as by facilities management practice. Higher education buildings in Thailand were utilised as a case study, and a series of student questionnaires were conducted involving a total 2,825 students in 11 Thai universities across six regions and observing 39 classes, 14 of which were instrumented and monitored during the survey. The study also included semi-structured interviews with 25 facilities managers in four universities. The findings generally supported the hypothesis and identify not only the criteria for students’ acceptance of assisted natural ventilation, but also the reasons behind the current facilities management operating practice in HE sector. Approximately 76% of students reported a willingness to accept (rather than not) the use of assisted natural ventilation in existing mixed-mode classrooms during the cool season if they perceived moderate-high opportunities (i.e. effective and probable) for using fans (3.3 times more willing than with perceived low opportunities) and windows (2.8 times more willing than with perceived low opportunities). The perceived opportunity to use fans increased when there was at least one fan per 20 students. During the hot season, 37% of students reported a willingness to accept (rather than not) the use of assisted natural ventilation if they perceived moderate-high opportunities to use fans (2.8 times more willing than with perceived low opportunities), had a high daily exposure to naturally ventilated environments (1.8 times more willing than with full air-conditioning exposure), and a low income (1.5 times more willing than with a high income). Students with high exposure to naturally ventilated environments also tended to have a high level of pro-environmental attitudes, but the direction of causality is not certain. The high level of pro-environmental attitudes could be a new driver of adaptive behaviours and the willingness to reduce air-conditioning use. Interviews with facilities managers revealed that their preference for a certain thermal operation mode appeared to be dominated by preferences for cool comfort of users with high organisational status and/or students on a high income. Universities participated in this study so far had no explicit targets of monitoring and reporting of energy use. Fans, the most effective adaptive device, had been gradually removed from many mixed-mode buildings, and facilities managers tended to rely on full air-conditioning to avoid user complaints and possible user performance drop. However, the study found that students in assisted naturally ventilated classrooms did not perceive their learning performance to be lower than those in air-conditioned classrooms, as long as they felt thermally comfortable. The risk of performance drop appeared to increase when the room air temperatures reached 31C, the upper limit of comfort boundary for fan-assisted naturally ventilated spaces. The findings highlight the gradual obsolescence of mixed-mode operation in the non-residential sector in a hot-humid climate. Air-conditioning reduction policy should target high-ranking people within organisations as their commitment is considered to be a key driver of changes in organisational thermal comfort practice. In this regard, monetary incentives alone for high-ranking and high-income users to reduce energy consumption may not be effective. Organisations should maintain the variability of thermal environments indoors and engage more with end-users to reduce air-conditioning use through practical adaptive behaviours. The key performance indicators of facilities management should not only focus on user satisfaction but also energy reduction achievement in order to encourage and empower the facilities managers to implement the more effective energy policies. Regarding the adaptive behaviours, organisations and building designers should be made aware that not specifying or removing fans could potentially shift mixed-mode buildings to fully air-conditioned operation because window opening alone could not always guarantee thermal comfort for the majority of users even in the cool season. Further research is needed to evaluate the thermal and energy performance of the existing mixed-mode non-residential building stock and the potential energy saving associated with applying assisted natural ventilation based on climate change scenarios. Practical guidelines in terms of effectiveness and practicality for mixed-mode building design and operation for hot-humid climates could then be developed. The links between pro-environmental attitudes and thermal experience needs further investigation in order to clarify the direction of the relationship. More studies using intervention approaches should be conducted to estimate the potential for user performance risks if using mixed-mode operations.
5

Energy efficiency in housing : drivers and barriers to improving energy efficiency and reducing carbon dioxide emissions in private sector housing

Altan, Hasim January 2004 (has links)
Global environmental degradation is one of the most serious threats facing humankind as a result of the expansion of its activities around the globe. Scientific evidence is growing that greenhouse gas emissions are having a noticeable effect on the earth's climate. Sustainable development has become a global issue and its life cycle influences the life cycles of the whole planet dramatically. As widely accepted, CO2 emissions are the most significant impact on global climate caused by the amount of energy consumed (Kyoto Protocol, 1997). The UK Government has signed the United Nations Framework Convention on Climate Change in 1992 and is therefore committed to reducing the emission of six greenhouse gases with carbon dioxide being the most significant to 12.5% lower than the 1990 levels (DEFRA, 2000). The Government has also indicated that it has an aim of further reducing the emissions with an eventual target of 20% below the 1990 levels by 20 10. Energy consumed by the UK building stock approaches 50% of the total while transport is responsible for 28% (DETR, 2000). Accordingly the energy used in housing stock is responsible for about 30% of overall emissions (Shorrock and Walters, 1998), which is a major contributor to global warming and therefore, improving energy efficiency and reducing carbon dioxide emission within housing stock is a key factor for long term sustainability in the built environment. This research aims to study the energy efficiency standards, CO2 emissions and energy ratings of privately rented, university controlled and approved properties within Sheffield. In general, properties in this particular sector account for about 15% of the total housing stock and demonstrate one of the worst conditions of housing standards in the UK (Revell and Leather, 2000). In this research however, properties analysed have shown better characteristics regarding energy efficiency standards especially when compared to the worst housing examples in the country. This is mainly due to properties being controlled and approved by the university standards/requirements, and resulted in achieving higher energy efficiency standards within the privately rented sector. Case study analysis carried out includes over 200 privately rented properties, showing dwelling conditions and examining efficiency of both water and space heating systems. iii Abstract As a global matter, environmental issues and good building design have also been increasingly important in the UK. For that reason, energy and environmental assessment methods for buildings have been developed in order to accomplish good building design, which could contribute considerably to reducing pollution and improving the environment. These assessment methods identify criteria for a range of issues also concerning the global, national and indoor environments. Due to the importance of building energy and environmental assessment methods, many components have to be discussed for the future of buildings and more emphasis should be paid to encouraging property developers to utilise the appropriate methods in order to design energy conscious buildings. Some of the existing methods concerning 'Environment and Healthy Building' developed and used in the country have been reviewed and discussed in the perspective of global effects. In this study, having chosen university-controlled properties would therefore help to utilise the university authority to take action effectively and play a key role in guiding energy efficiency improvements within privately rented properties. With university authority, potential improvements in these properties can be encouraged and implemented much effectively, whilst existing legislation and policies are inoperative to enforce retrospective energy standards in existing housing. Furthermore, this has a negative impact on private rented sector and comes into being a major barrier for this particular sector. Therefore, this is an opportunity that will not only increase energy standards of the housing stock in Sheffield, but also help to achieve the rate of improvement required by the Home Energy Conservation Act 1995 and reduce the overall energy consumption caused by the existing housing stock in the country.
6

Indoor air quality in selected new-build airtight dwellings : a UK case study

McGill, Grainne January 2016 (has links)
Awareness of the impacts of climate change, rising energy prices, fuel poverty and a demand for energy security have prompted significant changes in design thinking, construction practice and legislation aimed at reducing energy use and carbon dioxide emissions within the domestic sector. A fundamental feature of energy efficient building design is the incorporation of an airtight envelope, which helps to reduce uncontrolled airflow through the building structure. Whilst this minimises heat loss associated with infiltration, there is growing concern that the requirements for purpose-provided ventilation have not received due attention. This, in turn with an increasing dependence on mechanical ventilation systems to achieve adequate levels of ventilation, has resulted in significant concern and anxiety regarding the potential detrimental impact of energy efficient design strategies on the quality of indoor air. This study emerged with the principal aim of understanding and evaluating the relationship between energy efficient design strategies and indoor air quality in new-build UK social housing, using a Case Study approach. Four new-build energy efficient housing schemes were investigated, employing a variety of data collection techniques; including physical indoor air quality measurements (with simultaneous monitoring of external conditions), building surveys, occupant diaries and interviews with the building occupants, design teams, Housing Associations, and Mechanical & Electrical consultants. The evidence from this study suggests that the quality of indoor air in the Case Study dwellings was generally poor, which raises concerns regarding the potential implications on occupant health and wellbeing. Moreover, significant concerns were highlighted regarding the applicability of heat recovery ventilation for a social housing context. The findings provide much needed insight into indoor air quality in airtight dwellings, which may be used to aid the design of effective sustainable residential buildings that consider not only energy efficiency, but also adequately address occupant health and exposure to indoor air pollutants.
7

Modelling and validation techniques for bottom-up housing stock modelling of non-heating end-use energy in England

Lorimer, S. W. January 2012 (has links)
This thesis engages with different methods and validation techniques for bottom-up stock modelling of non-heating end-use energy of the residential sector. These end-uses are not the primary focus of current domestic energy models, and there is a unique opportunity to use actual electricity use data to build and validate models as electricity becomes exclusively used for these end-uses in England. The first contribution to knowledge is the creation of a validation set from aggregated electricity use data that has become available from small census areas of around 600 households using only areas with minimal estimated rates of electric heating. The second contribution is a method for using partial data from recent housing and energy surveys to update complete, but dated surveys by using household size and seasonal distributions. This enables a yearly updated model validated against actual aggregate energy use. This led to an annually updateable single-level model of non-heating end-use energy based on the predictors of household size measured by the number of rooms and the number of occupants. This uses linear regression on a square-root transformation of energy instead of the current natural logarithm transformation. The model is found to have a slight over-prediction (1.5%) of energy use when validated. The final contribution is an alternative approach where the model was allowed to vary on the household’s area. A hierarchical linear model of domestic energy was built based on 20 area classifications. There is a weak, but significant effect of additional energy use in households located inside area classifications with higher mean household sizes. This effect is highly significant when building age is taken into account. Although validation was difficult because building age data is limited, this result points to a neighbourhood-level influence that explains energy use beyond individual household size if precise location data can be made available.
8

Airborne particulate sampling : an in-depth review with specialised studies on welding fume

Stanton, D. W. January 1981 (has links)
No description available.
9

Studies of deposition on cooled tubes with special reference to coal-fired boilers

Cliffe, K. R. January 1969 (has links)
No description available.
10

Improvements to the design and development process for domestic condensing boilers

Humphris, C. C. January 1999 (has links)
This thesis outlines a new approach to the Design and Development (D&D) of domestic boilers at the manufacturing company Potterton Limited. The project need was born out of changes in the marketplace, where competitive pressures demanded improvements in efficiency, reliability and value for money (the three key success factors). Working under senior management several inter-related application areas were identified, leading to new research in both the application of Computational Fluid Dynamics (CFD), and the management of the design process. The initial work focussed on performing a competitor benchmarking exercise and design literature review, with the objective of developing a new boiler design and management system. The Systematic Design methodology was utilised to develop an improved design concept using the three key success factors. At this stage a commercial CFD package (CFX) was procured to form the basis of a design tool, and the original strategy modified to incorporate a full validation program against an existing Potterton boiler. Three additional investigations were identified to provide the information and technology necessary for producing an effective management system. A technique known as Quality Function Deployment was utilised to derive a better understanding of customer requirements. An NVQ based skills model was developed for proactively managing the training and development needs of engineers, and the future technology orientation of the company investigated under the smart design project. The focus of the CFD work has been on the development of methodologies capable of simulating the boiler functions of turbulent pre-mixing, combustion, sensible heat transfer and condensation formation, In-depth development programs are presented on each of these areas, with a consideration of geometry, mesh, physical models and validation against experimental data. All validation data has been collected from a smallscale experimental investigation, where pressure, velocity, temperature and turbulence data has been measured under both hot and cold operating conditions. For each function a recommended approach is presented which can be used to investigate and improve boiler performance in terms of the three key success factors. The combination of these functions will form the basis of a boiler analysis tool, which will be used at the company.

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