17 results for Anderson, TN

  • Alternatives control strategies for Building Integrated Photovoltaic/Thermal (BIPVT) system

    Abdul Wahab, H; Duke, M; Carson, JK; Anderson, TN (2013-04-16)

    Conference item
    Auckland University of Technology

    The use of energy in buildings is an ongoing concern, not only in NZ but worldwide. This concern has led to significant growth in the use of solar energy to provide heating and electricity generation. This paper presents the theoretical and experimental results of a novel building integrated solar hot water system; developed using commercial, long run roofing materials. This work shows that it is possible to achieve effective integration that maintains the aesthetics of the building. Building integrated thermal (BIT) system parameters are identified and implemented in the TRansient SYstem Simulation (TRNSYS) modeling environment. Validation result comparing the simulation in TRNSYS and real experimentation show that experimental and simulation responses are close to each other. The coupling of TRNSYS and Matlab/Simulink shows the possibility to use Matlab/Simulink for developing appropriate control strategies for BIT roofing systems. Furthermore in this paper, a Fuzzy Logic (FL) controller is implemented in a Fuzzy Integrated System (FIS) toolbox in a Matlab/Simulink model and linked into TRNSYS building integrated photovoltaic/thermal (BIPVT) system model. Preliminary simulation results are presented, which showed that the FL control strategies improved the energy performance of the BIPVT system and could be an effective way controlling building integrated solar energy systems.

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  • Natural convection heat transfer in V-trough solar concentrators

    Anderson, TN (2013-07-22)

    Journal article
    Auckland University of Technology

    Abstract The use of V-trough concentrators offers a simple approach to increasing the radiation incident on a solar receiver; this is particularly useful for increasing the temperature in thermal systems. However in order to accurately predict the performance of thermal systems under concentrated radiation, there is a need to understand the heat loss from them. This study experimentally shows that, for a laterally and longitudinally inclined enclosed V-trough concentrator, the natural convection heat loss can be predicted using an equation of the form Nu = aRab for Rayleigh numbers between 2 × 103 and 1 × 108. It is suggested that the relationship is a good representation of heat transfer in enclosed V-trough concentrators under most practical orientations, and thus lends itself for implementation into design models for V-trough concentrators.

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  • An assessment of base load concentrating solar thermal power generation for New Zealand

    Anderson, TN; Duke, M; Carson, JK (2011-08-08)

    Conference item
    Auckland University of Technology

    With increasing pressure being placed on traditional energy sources, both in terms of supply and also regulatory, there is an increasing need to explore alternative generation technologies. In global terms, solar energy has the potential to make a significant contribution to worldwide energy demands in the future. This study examines recent developments in the emerging field of concentrating solar thermal power generation and explores the potential for base load electricity generation using this technology in New Zealand.

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  • Condensation control in glazed flat plate solar water heaters

    Oshikiri, J; Anderson, TN (2012-11-26)

    Conference item
    Auckland University of Technology

    Glazed flat plate solar collectors offer a simple and cost effective approach to heating water. However, on clear nights solar collectors can transfer a significant amount of heat to the atmosphere by radiation. In areas with a cool climate and high relative humidity the radiation heat loss can lead to the temperature of the glazing often reaching the dew-point of the surrounding air, this leads to condensation developing on the glazing. If water condenses on the inside of the glazing and repeatedly drips onto the solar absorber this could lead to damage of the solar collector surface thus shortening its operating life. Also the build-up of condensation on the glazing can lead to the growth of mould, is visually displeasing to the owner, and means energy must be “wasted” to evaporate the moisture during the following day. This study aims to develop the understanding of the role that condensation plays on collector performance, as well as addressing ways of minimising the impact it has. In doing so it presents an experimentally validated, numerical model for determining the frequency of condensation in glazed flat plate solar water heaters. It shows that climatic factors including relative humidity, ambient temperature and wind speed determine the frequency of condensation for any given location. However, it also reveals that the frequency of condensation can be modified by altering the convection heat transfer coefficient inside the collector and most significantly by using low emissivity coatings on the glazing layer.

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  • An experimental investigation of turbulent forced convection heat transfer by a multi-walled carbon-nanotube nanofluid

    Piratheepan, M; Anderson, TN

    Journal article
    Auckland University of Technology

    Abstract In this work, a nanofluid based on multi-walled carbon nanotubes was formulated, and its heat transfer characteristics experimentally examined for turbulent flow in a straight tube. The experiments found that using the nanofluid resulted in an increase in pumping power and also a decrease in the observed convective heat transfer characteristics. This suggests that multi-walled carbon nanotube nanofluids in turbulent flows will actually impair heat transfer rather than improve it, and so may not be an appropriate heat transfer media in forced turbulent flows.

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  • Studies of control strategies for building integrated solar energy system

    Wahab, HA; Duke, M; Carson, JK; Anderson, TN (2011-11-25)

    Conference item
    Auckland University of Technology

    Research and development work on Building Integrated Solar Energy Systems (BISES) has become an area of growing interest, not only in New Zealand (NZ) but worldwide. This interest has led to a significant growth in the use of solar energy to provide heating and electricity generation. This paper presents the theoretical and experimental results of a novel building integrated solar hot water system developed using commercial long run roofing materials. This work shows that it is possible to achieve effective integration that maintains the aesthetics of the building and also provides useful thermal energy. The results of a 6.73m2 glazed domestic hot water systems are presented. The key design parameters of the Building Integrated Thermal (BIT) system were identified and implemented in a TRansient SYstem Simulation (TRNSYS) model. Validation results comparing the simulation in TRNSYS and real experimentation show that experimental and simulation responses are close to each other. The coupling of TRNSYS and Matlab/Simulink shows the possibility to use Matlab/Simulink for developing appropriate control strategies for BIT roofing systems. Preliminary Fuzzy Logic (FL) intelligent controller was implemented in a Fuzzy Integrated System (FIS) toolbox in a Matlab/Simulink model and linked into TRNSYS model. Further work is needed to identify and design advanced predictive control strategies for the Building Integrated Photovoltaic Thermal (BIPVT) solar system and determine how the performance can be optimized.

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  • The effect of mechanical surface treatment on the UV-Visible Reflectance of low cost solar thermal absorber materials

    Anderson, TN; Hilditch, T; Barnett, MR (2011-08-12)

    Conference item
    Auckland University of Technology

    The mechanical treatment of solar absorbers by rolling, surface roughening and polishing, and large scale texturing can significantly affect the absorption of solar radiation in the ultraviolet and visible range. In this study, the effect of a number of mechanical treatments was examined for a range of low cost absorber materials. It was found that mechanical deformation of the test materials by rolling had a minor impact on their reflectance characteristics. However it was found that surface roughening and the orientation of the roughness features with respect to incoming radiation had a significant effect of the reflectance of all materials.

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  • Investigating glazing system simulated results with real measurements

    Luther, M; Anderson, TN; Brain, T (2011-12-06)

    Conference item
    Auckland University of Technology

    Over the past decades there has been a great deal of research related to simulation programs that calculate glazing thermal performance. In this study, several glazing systems were designed using VISION 3 (University of Waterloo, 1992) and WINDOW-6 (Lawrence Berkeley National Laboratory, 2010). The systems were fabricated and experimentally tested in-situ for a summer month. It was found that in most cases the predicted results of the glass temperature matched those measured,though slight discrepancies were observed during periods of high solar radiation, particularly for more complex systems and systems with shading devices.

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  • Performance of a building integrated collector for solar heating and radiant cooling

    Anderson, TN; Duke, M; Carson, JK (2011-12-05)

    Conference item
    Auckland University of Technology

    Due to their limited temperature range, unglazed solar collectors have long been relegated to providing low cost heating in applications such as swimming pool heating systems. This limited temperature range is due to heat loss: firstly by convection to the surrounding air and secondly by radiant heat transfer to the cold sky. During the day an unglazed collector can be operated as a standard solar absorber to heat water in a storage tank. However, it is possible to take advantage of radiant cooling of unglazed solar collectors by operating them at night. Under night conditions when there is no solar radiation and the sky temperature is low, the collector can radiate heat to the sky and cool a cold storage tank to provide cooling in the building the following day. This study theoretically and experimentally examines the performance of a building integrated collector for heating and cooling and explores the contribution it can make to heating and cooling loads in typical New Zealand and Australian buildings.

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  • Development of a low cost photovoltaic/thermal solar concentrator for building integration (BIPVTC)

    Kunnemeyer, R; Duke, M; Anderson, TN; Carson, JK (2011-12-05)

    Conference item
    Auckland University of Technology

    The idea of concentrating solar energy to increase the output of photovoltaic and solar thermal collectors is an area that has received significant attention. However, the use of solar concentrators that form part of a building’s fabric is an area that has received little attention to date. In this study, the design of a novel building integrated photovoltaic/thermal solar concentrator (BIPVTC) is discussed. The design is theoretically analysed and the model validated with experimental data. The results show that BIPVTC offers improved electrical yields from both concentrating radiation onto the photovoltaic cells and also by actively cooling them. Also, it was shown that the BIPVT could be made of a durable (long life) stainless steel, rather than the more reflective aluminium, while still offering a noticeable increase in annual output.

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  • Assessment of thermal comfort near a glazed exterior wall

    Anderson, TN; Luther, M; Brain, T (2011-12-13)

    Conference item
    Auckland University of Technology

    In many highly glazed buildings, the thermal comfort of the occupants will tend to be related to the incoming solar energy and the solar heat gain coefficient of the glazing. Many real buildings tend to be deep relative their height and therefore, areas close to the facade receive a much greater amount of the incoming energy than those farther from it. In turn, this imbalance leads to occupants near the facade experiencing a high dissatisfaction with their thermal environment (near-facade zone). This study experimentally examines the thermal environment of occupants near the facade of a glazed building wall. It presents results for Fangers’ predicted mean vote (PMV) and the predicted percentage dissatisfied (PPD) and explores some options for improving the thermal environment in this near-facade zone.

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  • A combined optical, thermal and electrical performance model of a Building Integrated Photovoltaic/Thermal Concentrator (BIPVTC)

    Anderson, TN; Kunnemeyer, R; Duke, M; Carson, JK (2011-11-25)

    Conference item
    Auckland University of Technology

    The electrical output of concentrating photovoltaic devices is significantly affected by the temperature of the photovoltaic cells. The ability to actively cool photovoltaic cells under concentrated radiation allows their electrical efficiency to be maintained particularly during periods of high solar radiation when concentration offers the maximum benefit. In this study, the design of a novel photovoltaic/thermal solar concentrator for building integration (BIPVTC) is discussed. The optical, thermal and electrical performance of the collector was theoretically modelled and validated with experimental data. The results show that BIPVTC offers improved electrical yields from both concentrating radiation onto the photovoltaic cells and also by actively cooling them.

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  • Performance of an unglazed solar collector for radiant cooling

    Anderson, TN; Duke, M; Carson, JK (2013-09-06)

    Conference item
    Auckland University of Technology

    Under night conditions, when there is no solar radiation and the sky temperature is low, unglazed solar collectors can radiate heat to the sky thus cooling a storage tank to provide cooling the following day. This study theoretically and experimentally examines the performance of an unglazed solar collector for cooling. It shows that such systems can provide a cooling capacity in the order of 50W/m2 and are able to cool to well below the ambient temperatures experienced during the cooling season. Finally it explores the contribution such a system could make to cooling loads in typical New Zealand and Australian buildings.

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  • Performance of a V-trough photovoltaic/thermal concentrator

    Künnemeyer, R; Anderson, TN; Duke, M; Carson, JK (2014-02-19)

    Journal article
    Auckland University of Technology

    The idea of concentrating solar energy to increase the output of photovoltaic and solar thermal collectors is an area that has received significant attention. In this study, a design model for a V-trough concentrating photovoltaic/thermal solar collector was theoretically analysed and validated with experimental data. The results showed that the V-trough offered improved electrical yields from both concentrating radiation onto the photovoltaic cells and also by actively cooling them. Also, it was shown that the V-trough could be made of a durable (long life) stainless steel, rather than the more reflective aluminium, while still offering a 25% increase in incident radiation over a typical year. However it was noted that modifications would be needed to improve cooling and to increase the thermal efficiency by reducing heat losses.

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  • Hourly global solar irradiation forecasting for New Zealand

    Ahmad, A; Anderson, TN; Lie, T

    Journal article
    Auckland University of Technology

    With the growing use of solar thermal energy systems and small scale photovoltaic power generation by domestic users, there is increasing need to develop intelligent controllers that allow these users to efficiently manage the energy generated by these systems. Ideally these intelligent controllers will be able to forecast the availability and magnitude of the solar resource to plan in advance for periods when the solar irradiance magnitude is small or unavailable. In addition, the method used to provide this forecast needs to be adaptable to a range of timescales and locations. With this in mind, this study examined the possibility of providing a 24-h ahead forecast of hourly global solar irradiation in New Zealand using several approaches but with particular reference to nonlinear autoregressive recurrent neural networks with exogenous inputs (NARX). Hourly time series data for nine historic weather variables recorded over a three year period was used to train and test the forecasting methods for New Zealand’s largest city, Auckland. Results from forecasts based on the NARX were compared with an artificial neural network (ANN) based Multilayer Perceptron (MLP) method, a statistical approach using auto regressive moving average (ARMA) and a reference persistence approach. Predicted values of hourly global solar irradiation were compared with the measured values, and it was found that the root mean squared error (RMSE) was 0.243 MJ/m2 for the NARX method as compared to 0.484 MJ/m2, 0.315 MJ/m2 and 0.514 MJ/m2 for the MLP, ARMA and persistence approaches respectively. Subsequently the NARX approach was used to forecast global solar irradiation for other major cities across New Zealand. The results demonstrate the ability of the NARX approach to forecast irradiation values at a later time and across a number of different locations. As such it is foreseeable that such an approach could serve as the basis of a forecasting system in future intelligent controllers.

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  • Optimal sizing of a wind-photovoltaic-battery hybrid renewable energy system considering socio-demographic factors

    Tito, SR; Lie, T; Anderson, TN

    Journal article
    Auckland University of Technology

    The sizing of a stand-alone wind-photovoltaic-battery hybrid renewable energy system (HRES) is greatly influenced by socio-demographic factors however, few studies have examined how socio-demographic factors, as borne out by different electrical usage patterns, influence the size of HRESs. This paper investigates how these factors influence the optimal sizing of a stand-alone HRES using a hybrid optimization method to match the available renewable energy with the demand. In this regard, different energy usage patterns resulting from users socio-demographic profile have been investigated and used for the optimal sizing of a HRES. The results show that the electricity usage profile of a site has a significant impact on the sizing and design of the system. Further, the results illustrate that one can design a system that meets the demand profiles resulting from socio-demographic factors with a minimum unmet load; however, by optimizing systems to the users socio-demographic profile, significant cost savings can be made.

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  • Natural Convection in a Ventilated Bottom Heated Cubic Enclosure

    Norris, Stuart; Anderson, TN; Gillen, JC (2016-03-14)

    Conference item
    The University of Auckland Library

    The flow and heat transfer in a bottom heated ventilated cubic enclosure is studied experimentally, visualizing the flow field using particle image velocimetry, and numerically, using a finite volume computational fluid dynamics code. The experimental results reveal how the flow structure is dependent on the size of the opening in the enclosure. For an opening over the top 50% of one wall, the experimental visualization reveals a flow structure on the center plane of two counter rotating cells, which is also found in the computational model. The stability of the flow is examined by the numerical model, and a stability limit of Ra ~ 10 6 was found, below which the flow is stable, and above which the flow becomes oscillatory or irregular. The enclosure was modelled for a variety of opening locations, and the case where the opening was at the top of the enclosure gave the highest rates of heat transfer.

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