Energy and exergy analyses of a parabolic trough collector operated with nanofluids for medium and high temperature applications

Thermal performance of parabolic trough collectors (PTCs) can be improved by suspending nanoparticles into the traditionally used heat transfer fluids. In this work, a one-dimensional mathematical model is proposed to investigate the effect of various nanoprticles suspended in the working fluid for medium and high temperature PTCs. The major finding of this work is that the nanofluid enhances the thermal efficiency of the PTC slightly. High operating temperatures are more suitable for using nanofluids and generate higher relative gains of energy delivered. It is also found that the exergetic efficiency improvement is more important than energetic efficiency. The peak exergy efficiency is achieved by the CuO based nanofluid and is about 9.05%. The maximum daily relative gain of thermal energy delivered is found to be 1.46% by using 5% of Al2O3 in the base fluid. Optimal control of the operating conditions can lead to maximum energetic and exergetic performances of the PTC

5.1 Energy Auditing

International audienceThis chapter presents the fundamentals of energy auditing as one of the most important approaches for reducing energy losses and minimizing the damaging effects of climate change and global warming. It classifies energy audits according to their type and level and describes their general methodology and tools. A case study of an energy audit carried out in the cement industry is presented as an illustrative example. \textcopyright 2018 Elsevier Inc. All rights reserved

Energy Conservation Potential of an Energy Audit within the Pulp and Paper Industry in Morocco

International audienceAn energy audit is a primary step toward improving energy efficiency at the facility level and ensuring a clean production. The pulp and paper sector is one of the most energy-intensive industries in Morocco. This article aimed at identifying energy conservation opportunities at a Small and Medium-sized paper industry. The audit results together with their financial viability are presented regarding the analysis of energy consumption and electrical quality issues. The paper introduces an action plan for a more efficient energy use of some specific applications such as furnaces and compressed-air installations as well. The recommended energy efficiency measures have the potential of saving about 347.85 MWh of electrical energy and 101.78 MWh of thermal energy corresponding to reductions of 11.48% and 2.22%, respectively. The total investments related to the application of the action plan is approximately 290.53 kMAD and the global payback period does not exceed one year. It was also shown that a total quantity of 283.39 t of CO2 emissions can be saved annually

Post Energy Audit of Two Mosques as a Case Study of Intermittent Occupancy Buildings: Toward more Sustainable Mosques

Mosques are buildings with a unique occupancy schedule and special energy and water consumption scheme. Generally, this type of buildings lacks the application of energy efficiency solutions and sustainable guidelines during the conception, construction and the operation phase. Interestingly, these iconic edifices can play a key role in raising awareness for sustainability and promoting cleaner energy technologies. The first aim of this work is to present energy audit results, recommended energy savings solutions for two historical mosques in Marrakech (Morocco). A detailed discussion of the adopted solutions is presented and an economic assessment was performed. Then, a two-year energy savings evaluation was conducted for the two mosques. Conclusions about the adequacy of the proposed solutions is presented. The second part is dedicated to outline some guidelines and sustainable criteria to consider for establishing an international sustainable mosques label. The creation of a such sustainable label will encourage spreading sustainable best practices in mosques and other types of buildings. It will also help to compare sustainable performances of different mosques around the world by establishing an adapted sustainable rating system

Yearly Performance of Low-Enthalpy Parabolic Trough Collectors in MENA Region According to Different Sun-Tracking Strategies

International audienceSolar parabolic trough collector (PTC) is a very popular system in solar concentration technology, which is widely used for electric production and heat generation in industrial processes. In this paper, a validated mathematical model has been proposed to evaluate the performance of low-enthalpy PTC in five sites of the MENA region: Ouarzazate (Morocco), Gafsa (Tunisia), Jeddah (Saudi Arabia), Amman (Jordan) and Aswane (Egypt). A MATLAB program was developed to simulate the hourly thermal performance of the PTC under fluctuating climatic conditions. A particular attention has been given to the effect of the sun-tracking technique on the collector's performance. The model validation was carried out in two phases: first, by comparison with the results generated by the System Advisor Model software, and second by comparison with experimental data. In both cases, a very close agreement is obtained. The results have shown clearly that the tracking technique, climate and season of the year have a significant impact on the PTC performance. The best site for implementing such technologies was found to be Ouarzazate (Morocco) with a useful annual energy generation potential varying from 104.85 to 154.57 MWh. On December 24, the PTC operating in Ouarzazate using 0.2 kg/s mass flow rate, the outlet water temperature can achieve a maximum temperature of 70 °C using the full-tracking and N-S tracking techniques, while the outlet temperature does not exceed 46.5 °C using the E-W tracking. This temperature can reach 82 °C on July 07, by using the full-tracking and E-W tracking modes. From a general aspect, it was also concluded that the optimal cost-effective tracking strategy for the annual heat generation is the E-W polar tracking one independently of the geographical location. \textcopyright 2017 Elsevier Lt

Energy auditing

International audienceThis chapter presents the fundamentals of energy auditing as one of the most important approaches for reducing energy losses and minimizing the damaging effects of climate change and global warming. It classifies energy audits according to their type and level and describes their general methodology and tools. A case study of an energy audit carried out in the cement industry is presented as an illustrative example. \textcopyright 2018 Elsevier Inc. All rights reserved

Renewable Power Generation: A Supply Chain Perspective

In recent years, the transition to a more sustainable and clean system has focused on the accelerated development of renewable energy technologies. This transition can be perceived as a major priority, especially with the current environmental concerns, threatening various aspects of human life. The objective of this article is, therefore, to highlight the role of the supply chain in the renewable power generation sector. In this context, a detailed assessment of the supply chain contribution to the renewable energy sector is presented. Next, the performance of the renewable energy supply chain is qualitatively evaluated by illustrating the various barriers against continuing development, and the key measures are recommended to overcome these barriers. Then, the main factors influencing the performance of the supply chain are identified and key performance indicators related to the renewable energy supply chain are established to achieve high efficiency and sustainability performances in the power sector

Solar driven cooling systems: An updated review

International audienceThis paper presents a review of the available technologies to provide cooling from solar energy for boththermal and photovoltaic ways. Several multi-criteria performance indicators figuring in the literatureare presented followed by a pros and cons analysis of the different solar thermal cooling processes. Amarket study is also carried out to evidence the potential of these solar cooling technologies. Finally, anoverview of various solar cooling installations in Europe, Egypt and China is presented