Evaluation of the potential of harvesting heat energy from asphalt pavements
27 Jan 2011-International Journal of Sustainable Engineering (Taylor & Francis Group)-Vol. 4, Iss: 2, pp 164-171
TL;DR: In this paper, a macro-enabled spreadsheet has been developed that allows the user to input air temperature data as well as pipe location and cost parameters, and the end results are data on flow rate versus yearly savings and payback period.
Abstract: The potential of harvesting heat energy from asphalt pavement using a piping network with fluid flowing through it needs to be evaluated before spending a significant amount of time on planning details of design and construction. The key factors involved in this evaluation include the temperature of the pavement at the depth at which the system is being considered, as well as the temperature of the fluid used for harvesting the heat energy. Costs include those required for the system such as pumps and pipes, and cost of energy required for pumping. Taking all of the factors into consideration, a macro-enabled spreadsheet has been developed that allows the user to input air temperature data as well as pipe location and cost parameters. The end results are data on flow rate versus yearly savings and payback period. From these data, a user can easily determine whether the payback period is reasonable or not and could also evaluate the effect of the different parameters on the payback period. Examples of the ...
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TL;DR: In this paper, the authors synthesize the existing definition, physical mechanism, and typical cooling techniques of cool pavements, presenting the influence of these pavements on the urban thermal environment.
Abstract: Conventional impervious pavements have dark surface and large thermal inertia. During summertime they tend to absorb and store solar radiation but negate the evaporative cooling, contributing to the development of urban heat island (UHI). The idea of using cool pavements to mitigate the UHI has gained momentum recently. This review synthesizes the existing definition, physical mechanism, and typical cooling techniques of cool pavements, presenting the influence of cool pavements on the urban thermal environment. Benefits, penalties, costs and policies for the applications of cool pavements are presented with special emphasis on reflective pavements and evaporative pavements. The review suggests that the definition of cool pavements remain incomplete; that the influence of cool pavements on the air temperature in the urban canopy layer is unknown; and that the impact of cool pavements on the thermal conditions of adjacent buildings and pedestrians remains unknown. Many speculations of using cool pavements to battle the UHI effect need refinements and validations. Heat-harvesting pavements seem interesting because they not only stay cool but harness renewable energy. However, the results from the heat-harvesting pavement prototype require scrutiny on the power output, durability, and lifetime of the pavement system. Future studies are expected to understanding the impacts of cool pavements on pedestrian thermal stress, on adjacent building’s energy loads, and on the air temperature in the urban canopy layer.
405 citations
TL;DR: In this article, the authors summarized the major achievements of the existing literatures about the HAP and gave some proposals for further investigations, and confirmed the feasibility of harvesting solar energy, cooling the pavement, snow melting/deicing as well as air conditioning of buildings by applying innovation technologies on asphalt pavement.
Abstract: Solar energy is undoubtedly the environment friendly and inexhaustible energy resource for humans. The concept of hydronic asphalt pavement (HAP) is an emerging renewable energy technology, which provides an interesting method for solar energy utilization. The innovation of HAP is to mitigate a series of realistic problems related to the asphalt pavement as well as the depletion of fossil energy resource. Fluid circulating through the pipes network imbedded in the asphalt pavement can capture the solar energy and store for later use. This paper summaries the major achievements of the existing literatures about the HAP and gives some proposals for further investigations. Studies have confirmed the feasibility of harvesting solar energy, cooling the pavement, snow melting/deicing as well as air conditioning of buildings by applying innovation technologies on asphalt pavement. As seasonal energy storage technology is relatively mature at present, most of the literatures reviews focus on the influences of variables associated with system behavior as well as the heat transfer processes during snow melting and solar energy collection. Future work should aim to do more urgent issues involved with HAP application: construction technology, maintenance technology, and long-term performance. Solving these problems can strengthen the theoretical and practical understanding of HAP, and lead to more extensive applications.
258 citations
TL;DR: In this paper, the Pavement Solar Collector (PSC) is used to extract low temperature thermal energy, which is then stored in the PSC and used to harvest energy by flowing water through a heat exchanger.
77 citations
TL;DR: Statistical analysis result reveals that evaporation-enhancing permeable pavement can mitigate the UHI effect significantly more than a conventional permeable pavements.
75 citations
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TL;DR: In this article, the authors proposed a heat-mining method for asphalt pavements, using an appropriate fluid flowing in pipes installed within the pavement, to reduce pavement and near-surface air temperature.
Abstract: A rise in temperature of asphalt pavements contributes towards the urban heat island effect, causes problems with air quality and increases the power requirement for cooling buildings. A high temperature would also lead to the potential of rutting failure in asphalt pavements. The concept of mining heat from asphalt pavements, utilising an appropriate fluid flowing in pipes installed within the pavement, has been proposed. Theoretical considerations and results of laboratory testing and modelling simulation have been presented. The results indicate that the concept is feasible, and that the efficiency of heat mining can be improved by selecting appropriate surface layer and aggregates for pavement materials. The use of this proposed method would lead to a significant reduction in pavement and near-surface air temperature, and extension of asphalt pavement life.
142 citations
"Evaluation of the potential of harv..." refers background in this paper
...The concept of harvesting this heat energy from asphalt pavements has been presented earlier (Mallick et al. 2008, 2009) as shown in Figure 1....
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01 Jan 2003
TL;DR: In this article, the authors developed a design tool for the calculation of the thermal energy potential of a so-called asphalt collector and validated two types of numerical models against experimental results from a full-scale test site.
Abstract: This paper describes the development of a design tool for the calculation of the thermal energy potential of a so-called asphalt collector. Two types of numerical models have been developed and validated against experimental results from a full-scale test-site. The validation showed to be a tedious procedure due to the complexity of the full-scale testing of this type of systems. Nevertheless, the models are found to be applicable for performing design studies with. Example results presented in the paper indicate that the thermal energy potential of an asphalt collector is lower than that of a normal solar hot water system. The quality of the energy is also less. However, further advantages of the use of an asphalt collector are found in the reduced maintenance of the road and the avoidance of slippery roads in winter time. The latter is also an example of the heat exchanger capabilities of the asphalt collector.
44 citations
01 Jan 2008
TL;DR: In this paper, a finite element modeling and testing with small and large scale asphalt pavement samples was carried out to evaluate the efficiency of heat capture from asphalt pavements, and the results of small scale testing showed that the use of aggregates with high conductivity can significantly enhance the efficiency.
Abstract: The concept of extracting heat energy from asphalt pavements has been investigated in this study. The scope of work consisted of finite element modeling and testing with small and large scale asphalt pavement samples. Water flowing through copper tubes inserted within asphalt pavements samples were used as heat exchangers in the experiments. The rise in temperature of water as a result of flow through the asphalt pavement was used as the indicator of efficiency of heat capture. The results of small scale testing show that the use of aggregates with high conductivity can significantly enhance the efficiency of heat capture. The efficiency can also be improved by using a reflectivity reducing and absorptivity increasing top layer over the pavement. Tests carried out with large scale slabs show that a larger surface area results in a higher amount of heat capture, and that the depth of heat exchanger is critical. An effective heat exchanger design will be the key in extracting maximum heat from the pavement. 1. BACKGROUND The sun provides a cheap and abundant source of clean and renewable energy. Solar cells have been used to capture this energy and generate electricity. A more useful form of “cell” could be asphalt pavements, which get heated up by solar radiation. The “road” energy solar cell concept takes advantage of a massive acreage of installed parking lots, tarmacs and roadways. The heat retained in the asphalt mixture can continue to produce energy after nightfall—when traditional solar cells do not function. The idea of capturing energy from pavement not only turns areas such as parking lots into an energy source, but also could cool the asphalt pavements, thus reducing the urban heat island effect. The significance of this concept lies in the fact that the massive installed base of parking lots and roadways creates a low cost solar collector an order of magnitude more productive than traditional solar cells. The significantly high surface area can offset the expected lower efficiency (compared to traditional solar cells) by several orders of magnitude, and hence result in significantly lower cost per unit of power produced.
41 citations