A 50 year review of basic and applied research in radiant heating and cooling systems for the built environment

Fossil fuel energy resources are becoming increasingly scarce. Given the negative environmental impacts (e.g. greenhouse gas emissions) that accompany their use, it is hardly surprising that the development of renewable energies has become a major priority in the world today. Andalusia, with a mean solar radiation of 4.75 kWh/m 2 per day and a surface area of 87,597 km 2 , is the region in Europe with the highest solar energy potential. This research study determined the solar energy potential in Andalusia for grid-connected photovoltaic systems installed on residential rooftops. A methodology was developed for this purpose, which first involved a description of building characteristics, followed by the calculation of the useful roof surface area where photovoltaic arrays could be installed. In the next phase of the study, the mean solar irradiation characteristics were defined as well as the technical parameters of the photovoltaic systems. All of these factors allowed us to estimate the amount of electricity that could be potentially generated per year by solar panels.

Analysis of the photovoltaic solar energy capacity of residential rooftops in Andalusia (Spain)

Fossil fuel reserves are diminishing rapidly across the world, intensifying the stress on existing reserves day-by-day due to increased demand. Not only that, fossil fuels, presently contributing to 80% of world primary energy, are inflicting enormous impacts on environment. Climatic changes driven by human activities, in particular the production of greenhouse gas emissions, directly impact the environment. Energy sector has a key role in this regard since energy during its production, distribution and consumption is responsible for producing environmentally harmful substances. A secure and accessible supply of energy is thus very crucial for the sustainability of modern societies. There is an urgent need for a quicker switch over of energy systems from conventional to renewables that are sustainable and can meet the present and projected world energy demand. Solar power is one of the most promising renewables. It is reliable and less vulnerable to changes in seasonal weather patterns. Hydrogen, in the capacity of energy vector, is expected to be the optimum solution for intermittency and storage of energy produced by renewables. Thus, coupled with hydrogen as an energy carrier, solar energy has a large potential to become the fuel of the future. The present study is aimed to explore such potential for India in 2025. India is expected to have a high growth rate in energy demand over the coming years due to its huge population and rapid economic development. By the year 2020, the country's demand for commercial energy is expected to increase by a factor of 2.5. Presently, more than 90% of the energy demand is met by fossil fuels, in spite of the fact that India has limited fossil fuel resources as compared to global reserves. By the year 2020, India, presently the world's sixth largest energy consumer, is expected to meet 75% of its oil and gas needs by imports. Being an energy deficient country, it has not been able to keep up with demand, leading to power shortages and supply interruptions. The growing gap between the demand and supply of energy, and environmental externalities associated with fossil fuel require immediate and substantial increases in electric power generation and transmission capacities, and exploitation of new avenues of energy supply that are more stable and environment friendly. The geographic location of India makes it a strong candidate for harnessing solar energy. Thus, solar PV is a potential technology to meet India's future energy demand and its associated environmental challenges. The present work proposes solar hydrogen based energy network to meet the future energy demand for the major cities of India in a sustainable way. In the proposed energy network, solar PV produced electricity is to be utilized to meet the energy demand during day hours. The solar generated electricity that is excessive of demand is to be stored in the form of hydrogen to be utilized during nocturnal hours and prolonged overcast conditions. A modular approach has been adopted for the purposed energy network to meet the year 2025 demand of six major cities of India: Chennai, Delhi, Jodhpur, Kolkata, Mumbai and Trivandrum. Present as well as projected cost scenarios for 2025 have been provided for all the proposed technologies to evaluate the economical viability of the energy network under study. Based on the futuristic trends, it is foreseen that by the year 2025, the PV electricity would be more economical than the fossil fuel electricity.

Sustainable production of solar electricity with particular reference to the Indian economy

Waste-to-Energy (WTE) network synthesis for Municipal Solid Waste (MSW)

MSW has been identified as one of the alternative energy sources that can be used for electricity and/or power generation. This appears to be one enhanced channel to tackle MSW disposal problem. WTE concept is incorporated into the MSW management system in this work. The integrated system is modelled to study its practicability and significance. The proposed model is illustrated with a case study involving the supply network design and the utilisation of MSW from urban sources. The modelling steps involve the generation of a superstructure, mathematical model construction, optimisation and solution interpretation. The MSW availability and its utilisation are investigated through its supply network design. Optimal locations of processing hubs and facilities are determined. Following this, boundaries and sizes of the processing hubs are calculated. The benefits of WTE strategy from MSW is analysed and its energy generation potential is demonstrated. This WTE strategy acts as one potential MSW management scheme for all interested parties.

Waste-to-energy (WTE) Network synthesis from municipal solid waste (MSW)

A new design of a two-stage cycloidal speed reducer is presented in this paper. A traditional two-stage cycloidal speed reducer is obtained by the simple combination of singlestage cycloidal speed reducers. A single-stage reducer engages two identical cycloid discs in order to balance dynamical loads and to obtain uniform load distribution. Consequently, the traditional two-stage reducer has four cycloid discs, in total. The newly designed two-stage cycloidal speed reducer, presented in this paper, has one cycloid disc for each stage, that is, two cycloid discs in total, which means that it is rather compact. Due to its specific concept, this reducer is characterized by good load distribution and dynamic balance, and this is described in the paper. Stress state analysis of cycloidal speed reducer elements was also realized, using the finite elements method (FEM), for the most critical cases of conjugate gear action (one, two, or three pairs of teeth in contact). The results showed that cycloid discs are rather uniformly loaded, justifying the design solution presented here. Experimental analysis of the stress state for cycloid discs was realized, using the strain gauges method. It is easy to conclude, based on the obtained results, that even for the most critical case (one pair of teeth in contact) stresses on cycloid discs are in the allowed limits, thus providing normal functioning of the reducer for its anticipated lifetime. [DOI: 10.1115/1.4004540]

A New Design of a Two-Stage Cycloidal Speed Reducer

A practical approach to the optimization of gear trains with spur gears

Performances of low temperature radiant heating systems

Photovoltaic electricity production of a grid-connected urban house in Serbia

Cycloid drives belong to the latest generation of planetary gear trains. Their dynamic behavior was considered in this paper. On the basis of well-know dynamic models of involute toothed gearing with external and internal toothing, a dynamic model of a single-stage cycloid drive was developed. The differential equations of system motion were written and numerically solved in the MATLAB - SIMULINK software. The system excitation force was acting in the contact of a cycloid gear tooth and a stationary central gear roller. The diagrams are obtained showing the resulting displacements, corresponding velocity and dynamic force in terms of time. .

Mirko Blagojević

Papers

A New Design of a Two-Stage Cycloidal Speed Reducer

A practical approach to the optimization of gear trains with spur gears

Performances of low temperature radiant heating systems

Photovoltaic electricity production of a grid-connected urban house in Serbia

Analysis of cycloid drive dynamic behavior