Exergy-Optimum Coupling of Heat Recovery Ventilation Units with Heat Pumps in Sustainable Buildings

This study shows that as a result of exergy destructions in heat recovery ventilation units, additional but avoidable carbon dioxide emissions take place due to the imbalance between the unit exergy of thermal power recovered and the unit exergy of fan power required to overcome the additional pressure drop. Therefore, special attention needs to be paid in the design and control of heat recovery ventilation units to minimize such carbon dioxide emissions responsibility by a proper exergy-rational balance between the heat recovered and power required. The potential improvements about the exergy rationality of the heat recovery ventilation units were investigated for several alternatives. These alternatives were: heat recovery ventilation-only (base case), coupling with an airto- air heat pump in tandem or parallel to the heat recovery ventilation unit, and a heat pump-only case. To carry out such an investigation, a new exergy-optimum design and dynamic control model was developed. Under typical design conditions, this model showed that a heat pump in parallel configuration does not improve the exergy rationality unless its coefficient of performance is over 11, which is not practical with today’s technology. Instead, passive solar and wind energy systems have been discussed and recommended. Results were also compared with condensing boiler, micro-cogeneration unit, fuel cell, and electric resistance heating cases. It has been shown that heat recovery ventilation with an air-to-air heat pump in tandem is the best in terms of the exergy-based coefficient of performance. Additional comparisons were made concerning avoidable and direct carbon dioxide emission responsibilities, climate warming-potential and ozone-depleting potential, embodied energy, embodied exergy, and carbon dioxide recovery periods. A new composite index, which recognizes the direct relationship between the ozone layer depletion and the greenhouse gas emissions has also been introduced for comparing system alternatives in terms of their atmospheric footprint

Lessons Learned from Labyrinth Type of Air Preconditioning in Exergy-Aware Solar Greenhouses

An exergy-based model hypothesizes that labyrinth-type ground-to-air heat exchangers are responsible for carbon dioxide emissions if the exergy of power demand concerning ancillaries like fans and pumps exceeds the thermal exergy gain. This hypothesis was analyzed for a novel solar greenhouse proposal in northern Holland, primarily using heat pipes. Minimum electrical power demand without any need for fossil fuels were the main findings on a holistic basis. New definitions, namely nearly-zero-exergy greenhouse and nearly-zero carbon greenhouse, were developed with new metrics to quantify the hypothesis. Results show that the exergy approach provides crucial insight for the design of labyrinth-type ground-to-air heat exchangers and sets new constraints about limited environmental benefits

Benchmarking Energy Sustainability in Cities

Energy efficiency is a strategic component of urban sustainability. The aim of this workshop is to address benchmarking techniques in energy efficiency and sustainability as a management tool in the context of urban and local community actions towards sustainability. The workshop also identifies and discusses methodologies and tools to measure urban sustainable energy and energy efficiency in cities. It is well known that standard benchmarking techniques, such as per capita or GDP normalization, are missing important features of the collected data used for benchmarking. Rigorous benchmarking techniques are likely to play an increasingly important role for policy-making authorities and for local authorities to assess their energy efficiency actions, to monitor their performance, exchange experience and learn from each other. In order to develop reliable and robust benchmarking techniques, different databases on energy consumption and location should be integrated with statistical and energy performance assessment methodologies. A special session was dedicated to databases, methodologies and GIS based tools for assessing energy sustainability in urban areas

Preliminary analysis of dry-steam geothermal power plant by employing exergy assessment: Case study in Kamojang geothermal power plant, Indonesia

The objectives of this study are to perform the exergy analysis and ambient temperature optimization of the Kamojang geothermal power plant by employing Engineering Equation Solver (EES). The geothermal capacity is 55 MW and the field is vapor-dominated reservoir with temperature 245 °C. In the initial state temperature, pressure and mass flow data are collected from the plant operation. The study results show that system has overall efficiency of 35.86% which means that only 111,138.92 kW electrical power can be extracted from 309,000 kW thermal power being produced by 10 production wells of Kamojang. This low efficiency is due to irreversibility associated with different processes and components in the system. The largest irreversibility occurs in condenser due to which 53% of total energy is disposed into the environment. Ambient temperature at Kamojang varies from 17 to 20 °C. The effect of this variation in temperature is also investigated and it is observed that higher temperature does not have any significant impact on system efficiency

Proceeding of the Workshop "Benchmarking Energy Sustainability in Cities"

Energy efficiency is a strategic component of urban sustainability. The aim of this workshop is to address benchmarking techniques in energy efficiency and sustainability as a management tool in the context of urban and local community actions towards sustainability. The workshop also identifies and discusses methodologies and tools to measure urban sustainable energy and energy efficiency in cities. It is well known that standard benchmarking techniques, such as per capita or GDP normalization, are missing important features of the collected data used for benchmarking. Rigorous benchmarking techniques are likely to play an increasingly important role for policy-making authorities and for local authorities to assess their energy efficiency actions, to monitor their performance, exchange experience and learn from each other. In order to develop reliable and robust benchmarking techniques, different databases on energy consumption and location should be integrated with statistical and energy performance assessment methodologies. A special session was dedicated to databases, methodologies and GIS based tools for assessing energy sustainability in urban areas.JRC.F.7-Renewables and Energy Efficienc

System of Systems Simulation Driven Wildfire Fighting Aircraft Design and Fleet Assessment

Large wildfires are increasingly occurring phenomenon in several since the past few years. The suppression of wildfires is complex considering heterogeneous independent constituent systems operating together to monitor, mitigate, and suppress the fire. In addition, the management of the disaster response involve multiple institutions in collaboration. Recognition of this wildfire fighting scenario, as a System of Systems (SoS) is valid. Aerial vehicles may play a big role in firefighting considering monitoring and suppression at early stages when the fire is still small. Thus, there is scope for designing a new Unmanned Aerial Vehicle (UAV) with a payload of 250 kg to 500 kg for aerial forest fire suppression, using a SoS wildfire simulation driven aircraft design approach, where the individual optimum performance of a system, especially of a new aircraft for firefighting, does not guarantee optimum overall firefighting mission effectiveness. Whereas an optimum combination of fleet, technology and operational tactics can effectively suppress fire. For this reason, this research focuses on four different aspects: 1) Applying the inverse design paradigm to a wildfire suppression air vehicle by coupling a fire propagation cellular automata model with a stochastic agent-based simulation of an evolved firefighting SoS. An efficient SoS framework to Evaluate fleet performance. 2) Four System of systems – system – subsystem interlinking research questions are addressed with corresponding sensitivity results. The impact of wildfire based on vehicle fleet size, vehicle architecture (Tiltrotor, Compound Heli, Multirotor or Lift cruise), payload carrying capability, response time and cruise speed. 3) The evolution of perfect combination of aerial vehicle fleet with different vehicle architectures, technologies and performances using simulations. 4) Obtaining a set of system level (aircraft level) Measures of Performance (MoP) for the large suppression UAVs that produce improved SoS-level Measures of Effectiveness (MoE) during an initial attack quantified by containment time and total fire burnt area. As addressed by research questions and results. The response time and Number of Aircraft has large impact on success of the firefighting mission. As the time advantage deteriorate, the wild fire expands exponentially

Sensitivity analysis of aerial wildfire fighting tactics with heterogeneous fleets using a system of systems simulation framework

The rise in the average global surface temperature has caused wildfire seasons to expand leading to more incidents with severe intensities causing a significant increase in suppression expenditures, losses, and casualties. In addition, the larger number of wildfire incidents gives rise to higher carbon release that stays in the atmosphere, therefore, further intensifying global warming. Fire incidents vary substantially in complexity from the point of view of required and available firefighting means which makes for a challenging multi-level complex problem. System of Systems (SoS) approach can be used to investigate such problems taking into accounts various factors such as response time, firefighting tactics, fleet composition, available agents, and resources. This study uses a SoS simulation framework for overall wildfire suppression mission modeling. It builds upon the research previously performed by the authors by introducing: 1. An extensive analysis for the effect of wildfire environment parameters on fire spread. 2. Multiple suppression tactics which open the door to new solutions for wildfire fighting in addition to revealing nuanced trends at the system of systems level by using SoS framework. 3. A heterogeneous fleet composed of various suppression drones with different airframe configurations, payload capacity, flight velocity, and powertrain architecture

Digitalization and the Anthropocene

Great claims have been made about the benefits of dematerialization in a digital service economy. However, digitalization has historically increased environmental impacts at local and planetary scales, affecting labor markets, resource use, governance, and power relationships. Here we study the past, present, and future of digitalization through the lens of three interdependent elements of the Anthropocene: (a) planetary boundaries and stability, (b) equity within and between countries, and (c) human agency and governance, mediated via (i) increasing resource efficiency, (ii) accelerating consumption and scale effects, (iii) expanding political and economic control, and (iv) deteriorating social cohesion. While direct environmental impacts matter, the indirect and systemic effects of digitalization are more profoundly reshaping the relationship between humans, technosphere and planet. We develop three scenarios: planetary instability, green but inhumane, and deliberate for the good. We conclude with identifying leverage points that shift human–digital–Earth interactions toward sustainability

Numerical and experimental studies of a capillary-tube embedded PCM component for improving indoor thermal environment

This paper aims to analyse the thermal characteristics of a novel system of Capillary Tubes embedded in a Phase Change Material (CT-PCM) as part of active building environmental design for energy conservation and the improvement of indoor thermal environment. The CT-PCM system is proposed based on the concept that low-grade energy utilisation potential could be harnessed and maximised by buildings’ radiant heating/cooling systems and phase change material. The CT-PCM component is first built in the laboratory, and the thermal characteristics of the CT-PCM are investigated through a set of thermal response experiments. In addition, a simplified model is developed to assess the long-term thermal performance of the CT-PCM system for its application during a strategical system design stage. To ensure the robustness of the numerical model in the assessment of the thermal performance of the system, the developed model is evaluated against the experiments under a set of dynamic thermal boundary conditions. The evaluation process revealed that when the flow rate of thermal fluids in the CT-PCM system is more than 800 ml/min, the simulation results of the proposed simplified model is in a good agreement with the experiment. When the flow rate in the capillary tube is smaller than 800 ml/min, the correction factors are derived to address the non-uniformity of temperature distribution