Typical Spring Day Research Articles

Modeling of comprehensive power load of fishery energy internet considering fishery meteorology

Accurate calculation for comprehensive power load of fishery energy internet playsasignificantrolein reasonable using of energy and reducing environmental pollution. However, as fishery power load is of greatly unique meteorology sensitivity, it continues to be a difficult problem. Therefore, the research of fishery meteorology is an important part of the rational development of fishery resources, the protection of production safety, and the pursuit of high and stable yield. This paper makes a deep study on the power load of the fishery energy internet under the influence of fishery meteorology and takes onshore fish pond as the research object. First of all, the power load is divided into three parts: oxygen enrichment power load, feeding power load, and water replenishment and drainage power load. The impact mechanism of fishery meteorology (including temperature, surface wind speed, precipitation, relative humidity, etc.) on it is described, and then the overall power load is obtained through modeling and integration. Finally, taking the Yuguang Complementary Project in Zhouquan Town, Tongxiang, Zhejiang Province, China as an example, using the meteorological data of its typical spring day and using the MATLAB tool to solve, the hourly comparison of the three types of power loads, the comprehensive power load demand, the full-day electricity charge forecast and the total annual power consumption are calculated. The annual power consumption per hectare and per kilogram of output calculated by simulation are basically consistent with the order of magnitude of the survey data, which proves the validity of the model proposed. The model established in this paper is an original work, and the exploration of fishery energy internet can draw lessons from it.

Renewable Energy Communities in Islands: A Maltese Case Study

Renewable energy communities are considered as key elements for transforming the present fossil fuel-based energy systems of islands into renewable-based energy systems. This study shows how renewable energy communities can be deployed in the Maltese context to achieve higher penetration of residential-scale photovoltaic systems. Case studies for five renewable energy communities in the Maltese LV distribution network have been analyzed in detail. A novel community battery energy storage sizing strategy was proposed to determine the optimal storage capacity at each energy community. The main objective of the community battery storage in each REC is to minimize the reverse power injection in the grid (minimize the total reverse energy and reverse peak power values), as well as to reduce the peak evening electricity demand. The optimal sizes for communal BESSs were determined to be of 57 kWh (EC 1), 55 kWh (EC 2), 31 kWh (EC 3), 37 kWh (EC 4) and 10 kWh (EC 5), respectively. The community storage systems were observed to reduce the overall impact of all five energy communities on the grid infrastructure. Power system simulations were performed for a typical spring day to evaluate the impact of communal BESS placement on the node voltages for all five energy communities. The results showed that the community storage was more effective at reducing the node rms voltage magnitudes when deployed at the end of the respective energy communities, rather than at the beginning of the community. During peak generation hours, reductions of up to 0.48% in the node rms voltage magnitudes were observed. This contrasts with reductions of only 0.19% when the community storage was deployed at the beginning of the energy communities.

A multi agent-based optimal control method for combined cooling and power systems with thermal energy storage

Combined cooling, heating and power (CCHP) systems have been considered as a potential energy saving technology for buildings due to their high energy efficiency and low carbon emission. Thermal energy storage (TES) can improve the energy efficiency of CCHP systems, since they reduce the mismatch between the energy supply and demand. However, it also increases the complexity of operation optimization of CCHP systems. In this study, a multi-agent system (MAS)-based optimal control method is proposed to minimize the operation cost of CCHP systems combined with TES. Four types of agents, i.e., coordinator agents, building agents, energy management agents and optimization agents, are implemented in the MAS to cooperate with each other. The operation optimization problem is solved by the genetic algorithm. A simulated system is utilized to validate the performance of the proposed method. Results show that the operation cost reductions of 10.0% on a typical summer day and 7.7% on a typical spring day are achieved compared with a rule-based control method. A sensitivity analysis is further performed and results show that the optimal operation cost does not change obviously when the rated capacity of TES exceeds a threshold.

Development of a Coupled TRNSYS-MATLAB Simulation Framework for Model Predictive Control of Integrated Electrical and Thermal Residential Renewable Energy System

An integrated electrical and thermal residential renewable energy system consisting of solar thermal collectors, gas boiler, fuel cell combined heat and power, a photovoltaic system with battery, inverter, and thermal storage for a single-family house of Sonnenhaus standard is investigated with a model predictive controller (MPC). The main focus of this article is to define a multi-objective mathematical function, develop a coupled simulation framework for the nonlinear time-varying deterministic discrete-time problem of the energy system using TRNSYS and MATLAB. With the developed methodology, a sensitivity analysis of maximum optimization time, swarm (or population or mesh) size of a typical spring day and a typical summer day assuming a 100% accurate weather and load forecast with three different algorithms: particle swarm optimization (PSO), genetic algorithm (GA) and global pattern search (GPS) are analyzed. Finally, the obtained results are compared with a status quo controller. Results show that the PSO algorithm optimizer performs the best in this MPC for such a complex and time-consuming MPC model in both the spring day and the summer day. The obtained results show that the PSO with swarm size 50 in the selected typical spring day and the PSO with swarm size 40 in the selected summer day reduces the objective function’s fitness value from 413 to −177 within 6 h optimization time and from 1396 to 1090 in 4 h optimization time respectively.

Hybrid thermal energy storage with phase change materials for solar domestic hot water applications: Direct versus indirect heat exchange systems

A numerical model is developed and validated to simulate the performance of sensible energy storage (water tank) and hybrid energy storage (water tank including phase change material “PCM” modules) integrated into solar domestic hot water (DHW) system. Two configurations with direct heat exchange and indirect heat exchange using immersed heat exchangers are explored. A novel comparison is presented between both systems based on the solar fraction, which denotes the solar thermal energy contribution to the load. The effect of the storage volume on the solar fraction of the system is studied during a typical spring day while providing the hot water demands for a single-family residence, assuming a dispersed daily draw profile. The numerical results showed the crucial role of thermal stratification induced in the storage system with direct heat exchange. The storage system with direct heat exchange operates with 18–23% larger solar fraction than that with immersed coil heat exchangers. Adding PCM modules in the water tank with 50% volume fraction can yield around 40% potential reduction in the storage volume. The melting temperature of the PCM must be carefully chosen to maximize the energy storage in the latent form, thus limit the large temperature fluctuations of the system.

Improving thermal power of a cylindrical solar cooker via novel micro/nano porous absorbers: A thermodynamic analysis with experimental validation

In this paper, cylindrical solar cookers with microporous absorbers are experimentally and numerically investigated in terms of thermodynamic performance figures. For a typical spring day in Bayburt, which is a good example of continental climate in Turkey, a comprehensive thermal performance analysis is done for a cylindrical solar cooker. A mathematical model is developed to verify the accuracy of the measurements, which is applied to a solar cooker with conventional absorber, and a good accordance is achieved between numerical and experimental data. Afterwards, the model is utilised to analyse the impacts of porous absorbers on thermal performance parameters of cylindrical solar cooker with different porosity characteristics. In this respect, three porosity configurations (triangular, semi-circular and trapezoidal) are considered on the absorber surface, and the enhancement in thermal performance figures are evaluated through a computer code written in MATLAB. The results reveal that microporous absorbers play a key role in improving thermodynamic performance parameters of cylindrical solar cooker. According to the experimental results, energy and exergy efficiency of cylindrical solar cooker with ordinary absorber is found to be in the range of 27.7–17.0 and 17.9–11.5%, respectively. On the other hand, the said figures are enhanced to 30.4–18.7 and 19.9–12.8% with triangular porosity, 33.2–20.4 and 21.7–14.0% with semi-circular porosity, 34.6–21.2 and 22.6–14.6% with trapezoidal porosity. The time to boiling is also noticeably reduced via microporous absorbers, which is justified through a dynamic regression analysis.

Experimental and numerical investigation of cylindrical storage collector (case study)

An empirical and theoretical investigation was achieved on a cylindrical storage collector. It was suggested in this work for a cylinder to be cut at an inclined cutting plane. The tests were achieved for both summer and winter climate conditions with and without hot water removal. The hourly system performance parameters were investigated systematically for different experiments. These included the average storage temperature, velocity distribution, and temperature distribution.In the cylindrical collector, the ultimate magnitude of the average storage temperature was 25°C, while the maximum temperature at the tip of the cylindrical collector was 58°C for a typical spring day. Meanwhile, the rectangular collector can warm up the stored water to a temperature of 23°C, when the inlet water temperature was 12°C. The performance of the new solar collector was, in general, similar to the performance of the conventional thermosyphon flat plate solar water heaters.The Fluent program was used to confirm the experimental results. The free convection in the cylindrical collector was investigated based on the method of control volume. From the Fluent data and analysis of the collector, the temperature and velocity distributions throughout the day were obtained. The Fluent program data was well compatible with the experimental results.

Economic and environmental effects of peak regulation using coal-fired power for the priority dispatch of wind power in China

Wind curtailment is currently one of the major challenges in China’s renewable energy development. Technical solutions to wind curtailment could include more flexible power sources, storage and grid facilities. These, however, are long-term solutions due to physical, economic and institutional constraints. We argue that an effective short-term solution could be the full utilization of the technical potential of the existing power system, particularly by using China’s dominant coal-fired power capacity to provide peak regulation services for the priority dispatch of wind power.This paper assesses the economic and environmental effects of this approach. To this end, four scenarios are developed: Scenario I—full wind curtailment and average dispatch of coal-fired power, Scenario II—no wind curtailment and average dispatch of coal-fired power, Scenario III— no wind curtailment and optimal dispatch of coal-fired power, and Scenario IV —partial wind curtailment and optimal dispatch of coal-fired power. The economic and environmental effects under the four scenarios are then computed using the GAMS program based on the load curve on a typical spring day for a coal-fired power plant and a wind farm in China’s northeastern Harbin City. The results of our research show that whilst Scenario IV has the best economic effects, Scenarios III and IV have the best environmental effects. Scenario IV is considered the optimal solution as more economic benefits could be realized at the expense of smaller wind curtailment. Drawing on these results, it is recommended to amend the Renewable Energy Law to allow a small proportion of renewable energy curtailment; to enhance the flexibility of the existing coal-fired power units; to advance energy efficient power dispatch approach; and to incentivise coal-fired power to provide peak regulation services for renewable energy.

An optimization strategy for the control of small capacity heat pump integrated air-conditioning system

This paper studies the optimization of a small-scale central air-conditioning system, in which the cooling is provided by a ground source heat pump (GSHP) equipped with an on/off capacity control. The optimization strategy aims to optimize the overall system energy consumption and simultaneously guarantee the robustness of the space air temperature control without violating the allowed GSHP maximum start-ups number per hour specified by customers. The set-point of the chilled water return temperature and the width of the water temperature control band are used as the decision variables for the optimization. The performance of the proposed strategy was tested on a simulation platform. Results show that the optimization strategy can save the energy consumption by 9.59% in a typical spring day and 2.97% in a typical summer day. Meanwhile it is able to enhance the space air temperature control robustness when compared with a basic control strategy without optimization.

Three-dimensional transient heat transfer and airflow in an indoor ice rink with radiant heat sources

Three-dimensional mixed convection in an ice rink heated by thermostatically controlled radiant heaters was simulated numerically using the standard k–e model with wall functions. This large building was modelled under transient conditions by considering the real outdoors atmospheric conditions for a typical spring day in Montreal, Canada. Results indicate the usefulness of the CFD technique as a powerful tool which provides a detailed description of the flow and temperature fields as well as the heat fluxes into the ice. The most important results are: Heating is needed only during the night (from 22 h to 7 h) when the outdoors temperature is relatively low. The On/Off switching of the radiant panels influences the temperature profiles throughout the ice rink; even the ice surface temperature is affected although the view factor between these two surfaces is zero. The radiation heat flux towards the ice increases significantly when the radiant panels are turned On; this can influence ice quality. The resurfacing operation increases the ice temperature and, by convection, the temperature of the air immediately above the stands. The air near the ice surface (1 meter over the ice) is essentially stagnant and significant air velocities can only be found above the stands and near the ceiling above the ice. The volumetric flow rate and temperature of the air evacuated from the building vary significantly between the different outlets.

The role of organic condensation on ultrafine particle growth during nucleation events

Abstract. A new aerosol dynamics model (DMANx) has been developed that simulates aerosol size/composition distribution and includes the condensation of organic vapors on nanoparticles through the implementation of the recently developed volatility basis set framework. Simulations were performed for Hyytiälä (Finland) and Finokalia (Greece), two locations with different organic sources where detailed measurements were available to constrain the new model. We investigate the effect of condensation of organics and chemical aging reactions of secondary organic aerosol (SOA) precursors on ultrafine particle growth and particle number concentration during a typical springtime nucleation event in both locations. This work highlights the importance of the pathways of oxidation of biogenic volatile organic compounds and the production of extremely low volatility organics. At Hyytiälä, organic condensation dominates the growth process of new particles. The low-volatility SOA contributes to particle growth during the early growth stage, but after a few hours most of the growth is due to semi-volatile SOA. At Finokalia, simulations show that organics have a complementary role in new particle growth, contributing 45% to the total mass of new particles. Condensation of organics increases the number concentration of particles that can act as CCN (cloud condensation nuclei) (N100) by 13% at Finokalia and 25% at Hyytiälä during a typical spring day with nucleation. The sensitivity of our results to the surface tension used is discussed.

Enhancing Smart Grid realisation with accurate prediction of photovoltaic performance based on weather forecast

The energy conversion efficiency of photovoltaic (PV) panels depends on solar irradiance and cell temperature. The cell temperature is affected by ambient and sky temperature, wind speed and direction, in addition to solar irradiance. This study summarises relevant relationships in the literature and describes a method of calculating cell temperature and efficiency, based only on field-measured solar irradiance, ambient temperature and wind speed. These equations have been applied to a 500 kW PV site on a typical spring day and all results were within 1.6% of measured values, with an average error of 0.05%. This provides a predictive capability for solar PV to be efficiently integrated into a Smart Grid.

Downstream flows: From nearfield to wake

As they do every year, the AAAF's French-speaking aerodynamicians met for their annual symposium during the last week of March 2000. We took advantage of three very typical Spring days in Orleans to set up shop on the premises of the Ecole Superieure de l'Energie et des Materiaux (ESEM) at the University of Orleans. About the author

Gas exchange of Agropyron desertorum: diurnal patterns and responses to water vapor gradient and temperature.

The response of leaf gas exchange to environmental variables were measured at different levels of drought stress for Agropyron desertorum, a naturalized perennial bunchgrass of the semiarid shrub steppes of western North America. Leaf conductance (stomatal plus boundary layer) was more sensitive to changes in water vapor gradient than to changes in leaf temperature. Assimilation was sensitive to both temperature and vapor gradient, and also appeared to be affected by conductance and high transpiration rates. The magnitudes of both assimilation and conductance decreased with increased drought conditions. Diurnal patterns of gas exchange were measured during 3 growing seasons. For a typical spring day with moderate leaf temperature and vapor gradient, diurnal patterns were similar for plants at different levels of soil water availability. Assimilation was relatively constant during most of the day, but conductance decreased during the afternoon. Total daily carbon gain was decreased to a lesser extent than daily water loss as soil water was depleted. Consequently, the ratio of daily carbon gain to daily water loss, i.e. daily water use efficiency, increased with decreased soil water content for diurnals under spring conditions. Diurnal patterns of assimilation for a typical summer day with high leaf temperature and vapor gradient differend from those for a spring day. An afternoon decrease in assimilation was typical during a summer day. Daily carbon gain, water use, and water use efficiency for summer diurnals decreased only under severe drought conditions. Almost complete recovery of assimilation and conductance occurred if leaf microclimate was ameliorated during the afternoon of either spring or summer diurnals. Thus, conditions responsible for a midday depression in assimilation during a single day did not have persistent effects on leaf gas exchange. Daily carbon gain of a typical summer day was restricted by leaf microclimate during the afternoon, but daily water use efficiency was not relatively increased by the amelioration of leaf microclimate.

Fever and antipyresis in the lizard Dipsosaurus dorsalis.

Lizards (Dipsosaurus dorsalis) were placed in a desertlike environment in which the ambient temperature (Ta) at night (1800-0600 h) was 12 degrees C and the day (0600-1800 h) Ta was between 30 and 55 degrees C depending on the location within the chamber. When dead Aeromonas hydrophila (4 X 10(9) organisms) was injected into nine lizards, an elevation in body temperature (Tb) of 2.7 degrees C was observed during the same day. On the day after bacterial injection the lizards' body temperatures averaged 41.6 degrees C, an increase of 4.2 degrees C over their control day Tb. Further investigations on the febrile response of D. dorsalis were conducted at the University of Wisconsin's Biotron, where there exists a simulated desert environment with the light intensity, temperature, and humidity closely parelleling a typical spring day in the southwestern desert of the United States (the natural habitat of Dipsosaurus). In this environment injection of dead bacteria into seven lizards led to an average febrile response of similar magnitude (Tb = 40.5 degrees C) but with a longer latency than that found at the University of Michigan. Injection of 13 lizards with live A. hydrophila (5 X 10(9) organism subcut.) in the simulated desert at Michigan led to a daytime fever averaging 2.3 degrees C (mean Tb = 40.6 degrees C) over a 5-day period. During the 6th and 7th day the lizards' body temperature returned to the normal or afebrile level. Injections of sodium salicylate along with dead A. hydrophila resulted in a dose-dependent attenuation of the febrile response. These results demonstrate that the reptilian febrile response is strikingly similar to avian and mammalian fever and suggest a common origin and perhaps function for the febrile mechanism.