scholarly journals Modelica-Based Modeling and Simulation of District Cooling Systems: A Case Study

2021 ◽  
Author(s):  
Kathryn Hinkelman ◽  
Jing Wang ◽  
Wangda Zuo ◽  
Antoine Gautier ◽  
Michael Wetter ◽  
...  
Keyword(s):  
Carbon Dioxide Emissions ◽  
Large Scale ◽  
Cooling System ◽  
Object Oriented ◽  
College Campus ◽  
Cooling Systems ◽  
Source Models ◽  
Electricity Costs ◽  
And Control

While equation-based object-oriented modeling language Modelica can evaluate practical energy improvements for district cooling systems, few have adapted Modelica for this type of large-scale thermo-fluid system. Further, to our best knowledge, district cooling modeling studies have yet to include hydraulics in piping network nor waterside economizers. These are critical details to include when looking to make energy and control improvements in many physical system installations. To fi?ll these gaps, this study applies newly developed open-source models from the Modelica Buildings library. For a real-world case study, we modeled and simulated a district cooling system at a college campus in Colorado, United States, with six buildings connected to a central chiller plant featuring a waterside economizer. Several energy saving strategies are pursued based on the validated model, including control setpoint optimization, equipment modification, and pump setpoint adjustments. Results indicate that optimizing the condenser water supply temperature setpoint can save 2.5% to 4.4% energy; the nonintegrated waterside economizer saves 6.4% energy while cutting down the chillers' run times by 201 days/year, reducing maintenance costs, and extending chiller life; and adjusting the condenser water pump flow settings can save 10.2% energy. Through a combinationof the studied measures, the campus can annually save 84.6 MWh of energy, 8.9% of electricity costs, and 58.0 metric tons of carbon dioxide emissions. Further, the numerical results of simulating districts from tens to hundreds of buildings are presented.

Performance Analysis With Future Predictions of Different Solar Cooling Systems in Guayaquil, Ecuador

2014 ◽  
Author(s):  
Carlos Naranjo-Mendoza ◽  
Jesús López-Villada ◽  
Gabriel Gaona ◽  
Jerko Labus
Keyword(s):  
Flow Rate ◽  
Cooling System ◽  
Meteorological Data ◽  
Cooling Systems ◽  
Great Opportunity ◽  
Constant Flow Rate ◽  
Solar Cooling ◽  
Average Annual Temperature ◽  
System Configurations

This paper presents a comparative analysis of three different solar cooling system configurations developed for a case study building in Guayaquil, Ecuador. Guayaquil is a city located at the Ecuadorian coast with an average annual temperature of 25°C. The city’s need for air conditioning throughout the year and the relatively intense solar radiation provide a great opportunity for implementation of solar cooling systems. The first cooling system includes a 175 kWc single-effect absorption chiller powered by evacuated tubes solar thermal collectors. This system was compared with two 140 kWc compression chiller systems (air-cooled (AC) and water-cooled (WC)) powered by grid-connected photovoltaics. Both constant flow rate (CFR) and variable flow rate (VFR) of chilled water were analyzed. The three systems have to satisfy a cooling demand of the top floor in one governmental building (app. 1296 m2) which was selected as case study. Additionally, two 140 kWc conventional compression chiller systems (AC and WC) were included in the comparison as reference systems. Cooling demand of the building was simulated in EnergyPlus and coupled with the appropriate system configurations developed in TRNSYS. The weather file (TMY) was developed based on real meteorological data collected in the last decade. The present analysis was extended with the prediction scenarios for the years 2020, 2050 and 2080 using climate change adapted weather files.

scholarly journals A review of evaporative cooling system concepts for engine thermal management in motor vehicles

2016 ◽  
Vol 231 (8) ◽  
pp. 1126-1143 ◽  
Author(s):  
Soheil Jafari ◽  
Julian F Dunne ◽  
Mostafa Langari ◽  
Zhiyin Yang ◽  
Jean-Pierre Pirault ◽  
...  
Keyword(s):  
Thermal Management ◽  
Carbon Dioxide Emissions ◽  
Cooling System ◽  
Evaporative Cooling ◽  
Motor Vehicles ◽  
Past Century ◽  
Cooling Systems ◽  
Automotive Engine ◽  
Engine Cooling ◽  
Evaporative Cooling System

The evaporative cooling system concepts proposed over the past century for engine thermal management in automotive applications are examined and critically reviewed. The purposes of this review are to establish the evident system shortcomings and to identify the remaining research questions that need to be addressed to enable this important technology to be adopted by vehicle manufacturers. Initially, the benefits of the evaporative cooling systems are restated in terms of the improved engine efficiency, the reduced carbon dioxide emissions and the improved fuel economy. This is followed by a historical coverage of the proposed concepts dating back to 1918. Possible evaporative cooling concepts are then classified into four distinct classes and critically reviewed. This culminates in an assessment of the available evidence to establish the reasons why no system has yet been approved for serial production commercially. Then, by systematic examination of the critical areas in evaporative cooling systems for application to automotive engine cooling, the remaining research challenges are identified.

The Big-headed Ant Pheidole megacephala: a new threat to monsoonal northwestern Australia

1998 ◽  
Vol 4 (3) ◽  
pp. 250 ◽  
Author(s):  
Benjamin D. Hoffmann
Keyword(s):  
Agricultural Production ◽  
Large Scale ◽  
Foraging Ecology ◽  
Potential Threat ◽  
Pheidole Megacephala ◽  
Realistic Option ◽  
Northwestern Australia ◽  
Nature Park ◽  
And Control

The Big-headed Ant Pheidole megacephala is a major threat to native invertebrate assemblages and to agricultural production world-wide. This paper reviews its known biology including its foraging ecology, colony founding and dispersal behaviour. A case study is presented to illustrate its potential conservation significance for northern Australia. At Howard Springs Nature Park in the Darwin region of the Northern Territory, an infestation of P. megacephala was found to cover 25 ha and is continuing to spread, with its distribution centred on a rainforest patch. The abundance of P. megacephala within the rainforest was 37?110 times that of total native ant abundance at uninfested sites. Only two individuals of a single native ant species were found in the highest abundance of P. megacephala and abundance of other invertebrates was only 15% of natural levels. Pheidole megacephala is a serious potential threat to native biodiversity in monsoonal Australia. Successful eradication on a large scale is a realistic option and control methods are discussed, including chemicals and fire.

scholarly journals Thermofluid Modelling of Large-Scale Orchards for Optimal Design and Control of Active Frost Prevention Systems

Energies ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 378
Author(s):  
Ercan Atam ◽  
Se-Woon Hong ◽  
Alessia Arteconi
Keyword(s):  
Optimal Design ◽  
Control Systems ◽  
Large Scale ◽  
Initial Conditions ◽  
Minimum Energy ◽  
Prunus Armeniaca ◽  
Thermal Dynamics ◽  
Heating Systems ◽  
And Control

Accurate modelling and simulation of temperature dynamics in large-scale orchards is important in many aspects, including: (i) for the calculation of minimum energy required to be used in optimal design of active frost prevention energy systems (fully renewable or partially renewable) to prevent freezing of fruit flowers, buds, or leaves; (ii) for testing frost prevention control systems before real-implementation which regulate active heating systems inside orchards targeted to prevent frost. To that end, in this study, first, a novel and sophisticated parametric computational thermofluid dynamics (CTFD) model for orchard air thermal dynamics for different orchard parameters (such as fruit type, climate, number of trees, their sizes, and distance between them) and boundary/initial conditions was developed and validated with field data from the literature. Next, the use of the developed parametric CTFD model was demonstrated through a case study to calculate the minimal thermal energy required to prevent frost under different frost levels in a test Prunus armeniaca orchard located in Malatya, Turkey, which is the world capital for dry apricot production.

The Case Study on Optimization of Large Scale Heating and Cooling Network

2014 ◽  
Vol 525 ◽  
pp. 611-615
Author(s):  
Lan Bin Liu ◽  
Ai Juan Zou ◽  
Jia Jun Liao ◽  
Yu Fei Ma
Keyword(s):  
Temperature Difference ◽  
Large Scale ◽  
Cooling System ◽  
The Other ◽  
Water Load ◽  
System Parameters ◽  
Heating And Cooling ◽  
Return Water ◽  
Load Center

This paper discussed the optimization of two cases of large scale heating and cooling system. One is the heating/cooling system with heating/cooling source with distance from load center, the other is the heating/cooling system with heating/cooling source located in the load center. The affect of the temperature difference between supply and return water, load density and the price of energy towards optimized radius and max radius was discussed using the existed model. The optimized radius and appropriate system parameters are got. It is a reference to the designers and operators related.

Reactive tracers reveal hydraulic and control instabilities in full-scale activated sludge plant

2008 ◽  
Vol 57 (7) ◽  
pp. 1001-1007 ◽  
Author(s):  
D. Braun ◽  
W. Gujer
Keyword(s):  
Large Scale ◽  
Oxygen Sensor ◽  
Electrochemical Sensors ◽  
Aeration Tank ◽  
Control Loop ◽  
Reactive Tracers ◽  
And Control ◽  
Present Case Study ◽  
Aeration Control

The hydraulic characteristics of aeration tanks in WWTPs have a major impact on the degradation of pollutants, as well as on the control of the aeration. In particular in long reactors, which are not separated by baffles, hydraulic shortcuts or large scale recirculation can lead to a loss of performance. This work demonstrates that reactive tracers such as ammonium and oxygen can be used to investigate the hydraulics of aeration tanks in detail. With the use of electrochemical sensors it is possible to investigate effects in a broad range of time scales. In the present case study a slow oscillation of the aeration control loop was investigated. Large scale recirculation in the aeration tank and fast fluctuations of the ammonium concentrations close to the oxygen sensor were identified as the cause of these oscillations. Both, the recirculation as well as the fluctuation of the ammonium have a substantial influence on the performance of the aeration tank and the aeration control loop.

Mathematical Model for Spray Cooling Systems

1977 ◽  
Vol 99 (2) ◽  
pp. 279-283 ◽  
Author(s):  
H. A. Frediani ◽  
N. Smith
Keyword(s):  
Mathematical Model ◽  
Large Scale ◽  
Cooling System ◽  
Spray Cooling ◽  
System Model ◽  
Cellular Model ◽  
Cooling Systems ◽  
Cellular Analysis ◽  
Finite Difference Solution ◽  
Energy Equations

A mathematical model of a large-scale spray cooling system is described. The continuity and energy equations are developed for a cellular model representing a single spray in a system of sprays. The equations are solved using a finite-difference solution along a drop trajectory for both water and air parameters. The results of the cellular analysis are incorporated into a system model in which the interaction between sprays for both the water and air is considered. The model was used to simulate existing systems employing multiple rows of sprays, and the results of the calculations compare well with the available data.

OBJECT-ORIENTED ANALYSIS: CRITERIA AND CASE STUDY

1993 ◽  
Vol 03 (03) ◽  
pp. 319-350 ◽  
Author(s):  
J. DRAKE ◽  
W.T. TSAI ◽  
H.J. LEE ◽  
I. ZUALKERNAN
Keyword(s):  
Object Oriented ◽  
Hierarchical Structures ◽  
Data Transformations ◽  
Analysis Techniques ◽  
Analysis Technique ◽  
Object Models ◽  
And Control ◽  
Selection Of ◽  
Object Oriented Analysis

Three object-oriented analysis techniques: Shlaer & Mellor, Coad & Yourdon, and Document-Driven Analysis were evaluated. Criteria for comparison of analysis techniques were developed. These criteria state that an analysis technique should (1) cover data, transformation, and control perspectives of the problem, (2) address large problems through partitioning, bounding the problem, and supporting prototypes and incremental analysis, (3) provide approaches for verification and validation, and (4) support configuration control. A case study in a software engineering class was conducted using the three OOA techniques. Through the case study we found that (1) identifying objects is affected by notation and flexibility of object models, (2) visualizing global data, transformations, and control are necessary to capture end-user’s processes, (3) emphasizing hierarchical structures and third normal form divert the analyst’s attention from analysis to implementation, (4) an explicit representation of relationships is necessary, (5) peer review is useful in improving selection of objects and methods to support end-user processes, and (6) supporting a standard document from OOA products is not easy.

scholarly journals Power monitoring and control for large scale projects: SKA, a case study

2016 ◽  
Author(s):  
Domingos Barbosa ◽  
João Paulo Barraca ◽  
Dalmiro Maia ◽  
Bruno Carvalho ◽  
Jorge Vieira ◽  
...  
Keyword(s):  
Large Scale ◽  
Monitoring And Control ◽  
Power Monitoring ◽  
And Control

scholarly journals Energy-focused substantiation of the choice of an air conditioning system for an office and shopping building

2021 ◽  
Vol 11 (2) ◽  
pp. 38-45
Author(s):  
Anastasiya A. Frolova ◽  
◽  
Pavel I. Lukhmenev ◽  
Keyword(s):  
Power Consumption ◽  
Air Conditioning ◽  
Large Scale ◽  
Cooling System ◽  
Air Cooling ◽  
Outdoor Temperature ◽  
Cooling Systems ◽  
Air Conditioning System ◽  
Northern Areas ◽  
Conventional Cooling

Introduction. The air conditioning system is the main consumer of electricity inside office and shopping buildings. The coo­ling needs arise inside such buildings all over the year due to high amounts of heat emitted by people and equipment (computers, office equipment, cash registers), solar radiation (the envelopes of the majority of these buildings have continuous glazed facades) and sources of artificial lighting. A conventional cooling system has a compressor and condensers. The most important step towards an optimized and low-energy cooling system is the abandonment of compressor and condensers; in addition, the cold extracted from the outdoor air, is used in the system. This cooling technique is called an atmospheric co­oling system. The climatic features of Russia allow for a large-scale application of the cooling technology that uses natural cold. However, for a start, a decision was made to focus on a central region of the Russian Federation, namely, Moscow, rather than any northern areas of the country. Materials and methods. The problem is solved by the calculation method applied to the case of a 35-storey office building in Moscow. Various outdoor temperature options were considered as the bases for a transition to an atmospheric cooling system. The co-authors also compare different installation options for dry coolers, which in turn affect the routing length of refrigeration circuits. The annual demand for cold is calculated for all analyzed options. Results. Some results are presented in the form of tables of annual energy consumption by different types of air cooling systems. Conclusions. The co-authors have found that the location of dry coolers strongly affects the power consumption by a co­oling system. Power consumption by cooling systems was analyzed, and it was found out that transition to machine refrigeration at the higher outdoor temperature of +8 °C is more efficient from the standpoint of energy efficiency than the same transition at +5 and 0 °C.

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