Utilizing solar energy for anti-icing road surfaces using hydronic heating pavement with low temperature

During summer, the surface temperature of an asphalt road pavement can rise up to 70\ub0C due to absorbed solar radiation. The high temperature degrades the performance of the asphalt concrete by accelerating the thermal oxidation and plastic deformation, especially under heavy traffic loads. On the contrary, during winter, the temperature of road surfaces can reduce below the temperature of the ambient air due to the radiative heat loss. The low temperature hardens the asphalt pavement and makes it more susceptible to thermal cracking. Moreover, the low temperature causes the road surface to get slippery and hereby increases the risk for traffic accidents. A potentially environmental-friendly method to overcome the abovementioned problems is to use a Hydronic Heating Pavement (HHP). The HHP system consists of embedded pipes in the road. A fluid as thermal energy carrier circulates through the pipes. During sunny days, when the road surface is warm, the energy is harvested and saved in seasonal thermal energy storages. During cold days, the warm fluid from the storage is pumped back to the pipes to increase the surface temperature. The aim of this study is to investigate the feasibility of the HHP system for harvesting solar energy during summer and anti-icing the road surface during winter. The study is done in five different steps: (i) determining the thermal properties of three typical asphalt concrete used for the construction of roads in Sweden using experimental tests and numerical simulation models, (ii) developing a 2D numerical simulation model of the HHP system to find out the most suitable boundary condition equations associated with the heat transfer interactions between the road surface and surrounding climate as well as the initial results related to the required energy for anti-icing the road surface and remaining number of hours of the slippery condition on the road surface, (iii) developing a hybrid 3D numerical simulation model of the HHP system to obtain the fluid temperature decline along the pipes and the effects of the fluid flow rate on the performance of the HHP system, (iv) calculating the minimum required energy for anti-icing the road surface using optimization tools so no slippery condition remains on the road surface and (v) investigating the feasibility of the coupled HHP system to a Horizontal Ground Heat Exchanger (HGHE) for harvesting solar energy and anti-icing the road surface. The numerical simulation model of the HHP system is made based on the finite element method and validated by the experimental results and analytical solutions as well as by the results of the other numerical simulation models from literature. The results associated with the thermal properties show that the thermal conductivity of asphalt concrete can vary from 1 W/(m·K) to 3 W/(m·K). The results associated with the 2D numerical simulation model shows that the annual required energy for anti-icing is about 75 \ua0and the remaining number of hours of the slippery condition after heating the road surface is 128 hours. The results associated with the hybrid 3D numerical simulation model show that the annual required energy for anti-icing is about 84 \ua0and the remaining number of hours of the slippery condition after heating the road surface is 217 hours. The results associated with the optimization show that the minimum annual required energy for anti-icing the road surface is 107 \ua0which results in remaining only 3 hours of the slippery condition on the road surface. Furthermore, the results associated with the coupled HHP system to the HGHE show that the annual required energy for anti-icing is about 75 \ua0and the remaining number of hours of the slippery condition is 580 hours

Micro Simulation of the Elderly Population\u27s Effect on Iran\u27s Pedestrian\u27s Walking Flow

Since 1996 to 2006, Iran‟s population structure experienced considerable changes. During the mentioned period, the share of the population under 15 decreased from 39.6% to 28%. Considering this decrease, Iran‟s population was quickly guided to oldness which will have irreversible social and economical repercussions on the country‟s future progress. The main objective of this study is to estimate the effects of the elderly on the moving stream of the other pedestrians in Iran‟s sidewalks, which is done for the first time in Iran using the Micro-Simulation method. The Micro-Simulation model of pedestrians is a computerized simulation procedure in which the moving behavior of each pedestrian such as speed, path, and the direction is considered separately. According to the obtained results from this study, an increase in the percentage of the elderly population can lower the sidewalk\u27s level of service. Also, the decrease of the average motion speed and the free walking space for wider paths is not necessarily less than that of narrow paths; in a way that by increasing the width of a sidewalk, pedestrians‟ total average speed and the average walking space decrease up to a specific width and then, start to increase. This decrease in wider sidewalks is more than that in more narrow ones

Hydronic Pavement Heating for Sustainable Ice-free Roads

Hydronic pavement is an alternative method for de-icing of roads. A hydronic pavement (HP) could be more environmental friendly than traditional de-icing methods such as salting. The HP system consists of embedded pipes in the pavement structure, with a fluid as energy carrier. The performance of a HP system strongly depends on a number of parameters e.g. the location of the pipes, the thermal properties of pavement structure and the temperature level of the heat storage system. In this paper initial results related to the designing of a HP system are presented

Ice free roads using hydronic heating pavement with low temperature: Thermal properties of asphalt concretes and numerical simulations

A traditional method to mitigate the slippery conditions of a road is to spread out salt and sand on the road surface. However, salting causes corrosion on the road infrastructures, damage to surrounding vegetation and salification of fresh water. Hence, there is a need for alternative solutions to mitigate the slippery conditions. A renewable alternative is to use a Hydronic Heating Pavement (HHP). The HHP system consists of embedded pipes in the road. A fluid as thermal energy carrier circulates through the pipes. During sunny days, when the road surface is warm, the energy is harvested and saved in seasonal thermal energy storages. During cold days, the warm fluid from the storage is pumped back to the pipes to increase the surface temperature.The aim of this study is to investigate the performance of the HHP system for harvesting energy from the road surface during summer and anti-icing the road surface during winter. In the HHP system, the main part of the heat transfer occurs between the embedded pipes and the road surface. Hence, it is of importance to determine the thermal properties of the road materials. The thermal properties of a few Swedish typical asphalt concretes, used to construct the asphalt road pavements, were experimentally measured by the Transient Plane Source (TPS) method. The accuracy of the measurements of the TPS method was examined using different sensor sizes. Moreover, in order to investigate the effects of the different design parameters of asphalt concrete such as the types of aggregates on the thermal properties, a numerical model of asphalt concrete was developed. Comparing the obtained thermal properties by the numerical model and the experimental measurements exhibited that the relative error between two methods is in the range of 2% to 10%.Furthermore, in order to investigate the performance of the HHP system, a two-dimensional numerical model of the HHP system was developed based on the Finite Element Method (FEM). The developed numerical model was validated by two cases: (i) for the road without pipes, using a one year measured data and (ii) for the road with the embedded pipes, using analytical solutions. The validation results for the road without pipes showed that the annual mean difference of the temperature at the depth of 10 cm from the road surface is 0.1\ub0C with the standard deviation of 1.15\ub0C between the measured data and the numerically predicted temperature. The validation results for the road with the embedded pipes showed that the maximum relative error of the thermal resistance between the pipe and surface is less than 5% between the obtained results from the numerical model and the analytical solution. In order to investigate the harvesting and anti-icing performance of the HHP system, the climate data were selected from 6stersund in middle of Sweden, where there is an ongoing test site project to construct the HHP system in 2017. It was assumed that when the road surface temperature was lower than 0\ub0C, the heating was started to keep the surface temperature higher than the dew point temperature. The heating was stopped when the air temperature was below -12\ub0C. Based on the climate data, 90% of the slippery conditions on the road surface, due to condensation, occurred when the air temperature was above -12\ub0C. Furthermore, the air temperature was above 8\ub0C during 70% of the warm days (from the first of May to the end of September). The air temperature of 8\ub0C was taken into account to start harvesting energy from the road surface. The results showed that by maintaining constant fluid temperature of 6\ub0C through the pipes, 100 mm distance between the pipes and 3.5 m width of the road, the annual required energy for anti-icing the road surface is 356 kWh/(m\ub7year) and the annual harvested energy from the road surface was 1,047 kWh/(m\ub7year). Enhancing the thermal conductivity of road layers improves the harvesting and anti-icing performances of the HHP system

Användares erfarenheter av däckslitage hos elfordon : en enkät- och intervjustudie

Electrification of vehicles is considered as a solution to reduce climate gas emissions as well as locally emitted air pollution components due to zero exhaust emissions. Also brake wear emissions are expected to be reduced due to the use of regenerative2 braking. However, electric vehicles (EVs) have higher and more direct torque and can therefore accelerate fast. They are also generally heavier than equivalent internal combustion engine vehicles (ICEVs). These properties are hypothesized to lead to higher non-exhaust emissions from tyre and road wear as well as higher resuspension of road dust. On the other hand, driving behaviour in EVs might differ due to e.g. driving range issues.  This study aims at investigating users’ experiences with tyre wear of EVs, Plug-in Hybrid Electric Vehicles (PHEVs) and Hybrid Electric Vehicles (HEVs). The study was done using web-based inquiries and interviews. Two formats of surveys, one for private users and one for professional users were prepared. The professional survey included taxi, bus transport and car rental companies. The survey to private owners was communicated to the public using an ad on Facebook and the survey to professional users was sent by emails to companies. Furthermore, some interviews were done by professional users. 307 users answered the survey to private users and 28 companies answered the survey of professional users. Furthermore, six representatives for companies were interviewed.  The results showed that approximately 33% of private users and 12.5% of professional users experienced faster tyre wear in their EVs/HEVs/PHEVs, compared with tyre wear in ICEVs. Generally, for all electric vehicle types, most professional users experience similar tyre wear as for ICEVs. Vehicle acceleration and weight are the two most commonly mentioned reasons for faster tyre wear, while driving behaviour is the most commonly answered reason for slower tyre wear, compared to tyre wear in ICEVsElektrifiering av fordon betraktas som en lösning för att minska klimatgasutsläpp och lokala luftföroreningar på grund av minskade eller inga avgasutsläpp. Även bromsslitageemissioner förväntas minska på grund av användning av regenerativ1 bromsning. Elfordon (EV) har dock högre och mer direkt vridmoment och kan därför accelerera snabbt. De är också i allmänhet tyngre än motsvarande fordon med förbränningsmotorer (ICEV). Dessa egenskaper antas leda till högre utsläpp av slitagepartiklar från däck- och vägslitage samt högre uppvirvling av vägdamm. Å andra sidan kan körbeteendet i elbilar skilja sig åt på grund av oro för fordonens räckvidd i förhållande till laddningsmöjligheter.  Denna studie syftar till att undersöka användarnas erfarenheter av däckslitage på elbilar, plug-in elhybrider (PHEV) och elhybrider (HEV). Studien gjordes med hjälp av en webbaserad enkät och intervjuer. Två versioner av enkäten användes, en för privata och en för professionella användare. Den professionella enkäten omfattade taxi-, busstransport- och biluthyrningsföretag. Enkäten till privata användare kommunicerades till allmänheten med hjälp av en annons på Facebook och enkäten till professionella användare skickades via e-post till företag. Dessutom gjordes några intervjuer av professionella användare. 307 användare svarade på enkäten till privata användare och 28 företag svarade på enkäten till professionella användare. Vidare intervjuades sex företrädare för företag.  I allmänhet, för alla typer av elfordon, upplever de flesta professionella användare liknande däckslitage som hos fossildrivna fordon (ICEV). Cirka 33 % av privata användare och 12,5 % av professionella användare upplevde dock snabbare däckslitage i sina elbilar och elhybrider jämfört med däckslitage på ICEV. Kraftigare acceleration och högre vikt tas upp som de två viktigaste orsakerna till snabbare däckslitage, medan anpassat körbeteende tas upp som huvudorsaken till långsammare däckslitage

Pedestrians\u27 mental satisfaction\u27s relationship with physical characteristics on sidewalks using analytical hierarchy process: case study of Tehran, Iran

The aim of the current study is an examination of the relationship between the existing physical characteristics of sidewalks in Tehran, Iran, and pedestrians\u27 mental satisfaction. In order to successfully achieve this, physical and mental sidewalk characteristics were determined via expert elicitation and pedestrian investigations. Subsequently, 40 photographs of sidewalks located in Tehran were selected from all taken images, based upon photographic techniques; these were used to elicit data from 514 respondents via formally developed questionnaires. An analytical hierarchy process (AHP) was employed to analyze collated data. Results indicate that mental satisfaction is directly correlated with observed physical condition of sidewalks. It is concluded that sensitivity analyses such as those used in this study may be suitable for future optimization of sidewalk construction and maintenance; the presented approach may represent an appropriate model for increasing pedestrians\u27 satisfaction and is thus potentially of use to urban and peri-urban planners

Thermal properties of asphalt concrete: A numerical and experimental study

The aim of this study is to investigate the effects of different design parameters of asphalt concrete and environmental conditions on the thermal properties (thermal conductivity, diffusivity and volumetric heat capacity). A two-dimensional (2-D) numerical model of the asphalt concrete was developed based on the Finite Element Method (FEM). The numerical model was validated by the experimental results using the Transient Plane Source (TPS) method. The experimental results showed that an increase in the ratio of the TPS sensor size to maximum aggregate size improves the accuracy of the thermal properties measurements. A comparison between the thermal properties obtained by the numerical model and the TPS method exhibited a relative error in the range of 2–10%. The numerical model was used to study the effects of the type of aggregates, aggregate gradation, graphite filler in the binder, air void content as well as moisture and freezing conditions on the thermal properties of asphalt concrete

Hydronic Pavement Heating for Sustainable Ice-free Roads

Hydronic pavement is an alternative method for de-icing of roads. A hydronic pavement (HP) could be more environmental friendly than traditional de-icing methods such as salting. The HP system consists of embedded pipes in the pavement structure, with a fluid as energy carrier. The performance of a HP system strongly depends on a number of parameters e.g. the location of the pipes, the thermal properties of pavement structure and the temperature level of the heat storage system. In this paper initial results related to the designing of a HP system are presented

Hydronic Pavement Using Low Temperature Borehole Thermal Energy Storage

Winter conditions on roads are a challenge for road administrators in cold climates and with increased public demands on safety, winter maintenance activities will increase. The most common winter maintenance activity in Scandinavia is anti-icing, which is performed when it is a risk for ice formation on the road surface. Commonly a truck is utilized for spreading freeze point depressant, like salt, on the pavement thereby lowering the freezing point and preventing ice formation on the surface. This method has been questioned for a number of reasons e.g. salts have negative effects on the local environment. An alternative method for de-icing is to use hydronic pavement (HP). HP consists of a pipe network, embedded inside the pavement, in which a fluid is circulated. The fluid collect solar energy during summer days and transports heat back to the road surface during icy winter days. The harnessed and released energy should be in balance, otherwise an additional heat sources is needed. This study has investigated the possibility of developing an alternative strategy to heat the pavement surface with stored low temperature fluids. By using the methodology, and software BRIDGESIM, a preliminary design of a hydronic pavement system have revealed that it is not feasible to design a system for the cold climate of 6 stersund (Sweden); only relying on harnessing solar energy and store the energy in a borehole thermal energy storage. However it was revealed that it is possible to design HP system for low supply temperatures of about 7 \ub0C. Which is far below the supply temperature of about 35 \ub0C, recommended by manufacturers of HP system. The prospect of utilizing low-temperature heat sources would make HP system more energy efficient which could make it an alternative to traditional winter maintenance methods

Hydronic Pavement Using Low Temperature Borehole Thermal Energy Storage

Winter conditions on roads are a challenge for road administrators in cold climates and with increased public demands on safety, winter maintenance activities will increase. The most common winter maintenance activity in Scandinavia is anti-icing, which is performed when it is a risk for ice formation on the road surface. Commonly a truck is utilized for spreading freeze point depressant, like salt, on the pavement thereby lowering the freezing point and preventing ice formation on the surface. This method has been questioned for a number of reasons e.g. salts have negative effects on the local environment. An alternative method for de-icing is to use hydronic pavement (HP). HP consists of a pipe network, embedded inside the pavement, in which a fluid is circulated. The fluid collect solar energy during summer days and transports heat back to the road surface during icy winter days. The harnessed and released energy should be in balance, otherwise an additional heat sources is needed. This study has investigated the possibility of developing an alternative strategy to heat the pavement surface with stored low temperature fluids. By using the methodology, and software BRIDGESIM, a preliminary design of a hydronic pavement system have revealed that it is not feasible to design a system for the cold climate of 6 stersund (Sweden); only relying on harnessing solar energy and store the energy in a borehole thermal energy storage. However it was revealed that it is possible to design HP system for low supply temperatures of about 7 \ub0C. Which is far below the supply temperature of about 35 \ub0C, recommended by manufacturers of HP system. The prospect of utilizing low-temperature heat sources would make HP system more energy efficient which could make it an alternative to traditional winter maintenance methods