saffa riffat
University of Nottingham, Architecture & Built Environment, Faculty Member
Research Interests:
ABSTRACT The high energy demand to accommodate heating and cooling in buildings has put tremendous pressure on research to develop more ‘greener’ heating and cooling systems. The conventional vapour compression systems became desirable... more
ABSTRACT The high energy demand to accommodate heating and cooling in buildings has put tremendous pressure on research to develop more ‘greener’ heating and cooling systems. The conventional vapour compression systems became desirable for new and existing buildings for heating and cooling application because the system is well developed and commercially available. However, these conventional systems consume high energy and are considered not environmentally friendly with the usage of hydrofluorocarbons as refrigerants. On the other hand, thermochemical adsorption heat pumps are thought to be alternative solutions. However, some limitations such as low thermal conductivity in the adsorbent bed is one of the problems that this new technology would face in competing with the conventional heating and cooling systems. Thus, this review would emphasize on various techniques investigated by many researchers on solving low thermal conductivity and the various methods on enhancing heat and mass transfer in the adsorbed bed/pipe. Some of the common techniques that are used to enhance heat and mass transfer in the adsorbed bed/pipe include introduction of fin type adsorbent tube/ heat exchanger, amalgamated adsorbent bed with metal foam, consolidated adsorbent, adsorbent coating and adsorbent with multi cooling tubes. However, hitherto, the reviewed concluded that the embedding of the adsorbent material into the heat exchanger might be the most promising method that would attain better cooling power.
The installation cost and coefficient of performance (COP) of a ground source heat pump (GSHP) system can be greatly affected by the design of its ground loop. An experimental investigation was conducted to compare the performance of two... more
The installation cost and coefficient of performance (COP) of a ground source heat pump (GSHP) system can be greatly affected by the design of its ground loop. An experimental investigation was conducted to compare the performance of two loop designs for use with the ground source heat pump of an ‘energy pile’ installation or a conventional borehole system. A coaxial loop (a 40 mm OD coaxial tube with a 20 mm OD interior pipe) and a U-tube (20 mm OD pipes) of a length of 72 m were constructed, tested and analysed in terms of ground heat extraction capability and hydraulic flow characteristics. The use of the coaxial loop design could potentially reduce the cost of drilling boreholes and make the installation easier on site, as the effective diameter would be smaller than a comparable U-tube with the same mass flow rate, considering that the U-tube requires a minimum 10 mm spacer between the legs. Hydraulic performance tests have shown that the U-tube achieved the transitional-turbulent flow at a glycol flow rate of approximately 0.14L/s, whereas the flow in the coaxial remained laminar across the glycol flow rate range of 0.05–0.25L/s. Heat pump performance tests have shown that the U-tube achieved a COP of at least 0.08 greater than the coaxial loop across the range of glycol flow rates investigated, while the heat output was at least 12% greater when using the U-tube. Therefore, it can be concluded that the coaxial loop in its current form is seen not to add any performance benefit against the U-tube.► A coaxial loop could reduce cost of drilling and installation comparing with U-tube. ► A coaxial loop and a U-tube of a length of 72 m constructed and tested with a GSHP. ► The U-tube’s COP and heat output were 0.08 and 12% greater than the coaxial loop. ► The coaxial loop in its current form has no performance benefit against the U-tube.
Research Interests:
Research Interests:
This paper presents results of tests carried out to investigate a passive technology based on integration of a thermal diode and thermoelectric modules for a novel heat pump. The system is very compact and suitable for incorporation... more
This paper presents results of tests carried out to investigate a passive technology based on integration of a thermal diode and thermoelectric modules for a novel heat pump. The system is very compact and suitable for incorporation within the building structure. The heat pump uses thermoelectric modules to produce cooling or heating, and a new type of thermal diode to transfer heat into or out of the building, while preventing reverse heat flow in the event of power failure. Following design and construction of a thermoelectric heat pump prototype, its performance was investigated for two different modes, i.e., cooling and heating, under various operating conditions and environmental temperatures. Results showed that reducing the temperature of the thermal diode condenser could provide a significant improvement in the efficiency of the thermal diode and the coefficient of performance (COP) of the system in cooling mode. This can be achieved using the evaporation of water on the heat sink attached to the condenser. The experimental results showed that the new type of thermal diode worked effectively in both cooling and heating modes.
Research Interests:
ABSTRACT
Research Interests:
Research Interests:
Research Interests:
Research Interests:
... Titre du document / Document title. Computer simulation and experimental analysis of working fluids for absorption cycles. Auteur(s) / Author(s). RIFFAT SB (1) ; JAMES S. (1) ; Affiliation(s) du ou des auteurs / Author(s)... more
... Titre du document / Document title. Computer simulation and experimental analysis of working fluids for absorption cycles. Auteur(s) / Author(s). RIFFAT SB (1) ; JAMES S. (1) ; Affiliation(s) du ou des auteurs / Author(s) Affiliation(s). ...
Research Interests:
The paper describes a novel mop fan with flexible fibre impeller for use in livestock buildings. The mop is irrigated with a continuous supply of water to the eye of the shaft via a narrow bore pipe. The fan is designed to remove... more
The paper describes a novel mop fan with flexible fibre impeller for use in livestock buildings. The mop is irrigated with a continuous supply of water to the eye of the shaft via a narrow bore pipe. The fan is designed to remove particulate and gaseous pollutants from air, without resorting to filters, and may have potential for ventilating livestock
Research Interests:
Résumé/Abstract Piled foundations for residential buildings have predominantly been used in areas where conventional trench footing foundations have not been possible. The reasons for this have included loose and unstable overburden and... more
Résumé/Abstract Piled foundations for residential buildings have predominantly been used in areas where conventional trench footing foundations have not been possible. The reasons for this have included loose and unstable overburden and contaminated ground, ...
Research Interests:
SYNOPSIS This paper presents experimental performance of an ejector refrigeration system using methanol as the working fluid. The work is part of a research project to investigate and develop passive ejector refrigeration using natural... more
SYNOPSIS This paper presents experimental performance of an ejector refrigeration system using methanol as the working fluid. The work is part of a research project to investigate and develop passive ejector refrigeration using natural "environmentally friendly" fluids. The ...
Research Interests:
Research Interests:
... for various controlled conditions Xiaoli Ma Ã,y, Wei Zhang, SA Omer and SB Riffat Department of Architecture and Built Environment, Institute of Sustainable Energy Technology, University of Nottingham, Nottingham NG7 2RD, UK SUMMARY ...
Research Interests:
This paper presents monitoring results of two examples of building integrated PV system investigated at the School of the Built Environment, University of Nottingham in the UK. One of the systems is installed on an educational building,... more
This paper presents monitoring results of two examples of building integrated PV system investigated at the School of the Built Environment, University of Nottingham in the UK. One of the systems is installed on an educational building, and consists of a thin film PV façade appropriate ...
Research Interests:
ABSTRACT This paper presents a review of the latest developments on phase change materials (PCMs) for thermal energy storage (TES) applications in buildings. The paper provides information about material requirements for TES,... more
ABSTRACT This paper presents a review of the latest developments on phase change materials (PCMs) for thermal energy storage (TES) applications in buildings. The paper provides information about material requirements for TES, classification of PCM, mathematical modelling and applications of PCMs.
Research Interests:
Integration of natural ventilation and daylighting in a single installation would make both technologies more attractive. One method for the integration is the use of concentric light pipe and ventilation stack. By constructing the light... more
Integration of natural ventilation and daylighting in a single installation would make both technologies more attractive. One method for the integration is the use of concentric light pipe and ventilation stack. By constructing the light pipe using dichroic materials, the infrared part of the solar ...
Research Interests:
INTERNATIONAL JOURNAL OF ENERGY RESEARCH Int. J. Energy Res. 2009; 33:9991004 Published online 12 March 2009 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/er.1531 ... Investigation of energy transportation capability... more
INTERNATIONAL JOURNAL OF ENERGY RESEARCH Int. J. Energy Res. 2009; 33:9991004 Published online 12 March 2009 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/er.1531 ... Investigation of energy transportation capability of a phase change ...
Research Interests:
Research Interests:
The work described in this report was carried out under contract as part of the New & Renewable Energy Programme, managed by ETSU on behalf of the Department of Trade and Industry. The views and judgements expressed .in this report... more
The work described in this report was carried out under contract as part of the New & Renewable Energy Programme, managed by ETSU on behalf of the Department of Trade and Industry. The views and judgements expressed .in this report are those of the contractor and do not ...
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
ABSTRACT A novel solar-powered ejector air-conditioning system with a nominal capacity of 5 kW cooling is described in this chapter. The system comprised an evacuated tube solar collector system, an ejector cooling system, and an MEPCM... more
ABSTRACT A novel solar-powered ejector air-conditioning system with a nominal capacity of 5 kW cooling is described in this chapter. The system comprised an evacuated tube solar collector system, an ejector cooling system, and an MEPCM cooling storage system. The full size system has been laboratory tested, and the results are in good agreement with CFD simulation. A COP of up to 0.32 is obtained for the ejector cooling system during the test at the boiler temperature around 90 °C. Coefficient of performance of is up to 0.16 is predicted for the integrated system in operation. Guidelines for the design of system components based on the results of computer modeling and laboratory testing is given. Related correlations between these parameters will be obtained and presented in an easy step-by-step manner, in order to facilitate design and integration of system components for various applications. These will include analytical equations to match climate conditions and building air-conditioning load.
Research Interests: Multidisciplinary and CoP
Research Interests:
Research Interests:
Research Interests:
This paper presents monitoring results of two examples of building integrated PV system investigated at the School of the Built Environment, University of Nottingham in the UK. One of the systems is installed on an educational building,... more
This paper presents monitoring results of two examples of building integrated PV system investigated at the School of the Built Environment, University of Nottingham in the UK. One of the systems is installed on an educational building, and consists of a thin film PV façade appropriate ...
Research Interests:
This paper presents results of tests carried out to investigate the potential application of heat pipes and phase change materials for thermoelectric refrigeration. The work involved the design and construction of a thermoelectric... more
This paper presents results of tests carried out to investigate the potential application of heat pipes and phase change materials for thermoelectric refrigeration. The work involved the design and construction of a thermoelectric refrigeration prototype. The performance of the ...
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
ABSTRACT
Research Interests:
INTERNATIONAL JOURNAL OF ENERGY RESEARCH Int. J. Energy Res. 2009; 33:9991004 Published online 12 March 2009 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/er.1531 ... Investigation of energy transportation capability... more
INTERNATIONAL JOURNAL OF ENERGY RESEARCH Int. J. Energy Res. 2009; 33:9991004 Published online 12 March 2009 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/er.1531 ... Investigation of energy transportation capability of a phase change ...
Research Interests:
Research Interests:
... for various controlled conditions Xiaoli Ma Ã,y, Wei Zhang, SA Omer and SB Riffat Department of Architecture and Built Environment, Institute of Sustainable Energy Technology, University of Nottingham, Nottingham NG7 2RD, UK SUMMARY ...
Research Interests:
Research Interests:
Research Interests:
Research Interests:
*Correspondence to: Sa!a Ri!at, Institute of Building Technology, School of the Built Environment, University of Nottingham, Nottingham NG7 2RD, UK RE-mail: Sa!a.Ri!at@nottingham .ac.uk Contract/grant sponsor: Commission of the European... more
*Correspondence to: Sa!a Ri!at, Institute of Building Technology, School of the Built Environment, University of Nottingham, Nottingham NG7 2RD, UK RE-mail: Sa!a.Ri!at@nottingham .ac.uk Contract/grant sponsor: Commission of the European Union (DG XII).