Multi-Circuit Air-Conditioning System Modelling for Temperature Control

The suitable application of innovative control strategies in Heating, Ventilation, and Air-conditioning systems is important to improving the energy efficiency and maintenance of temperature set point to improve thermal comfort in buildings. The increased focus on energy savings and appropriate thermal comfort has resulted in the necessity for more dynamic approach to the use of these controllers. However, the design of these controllers requires the use of an accurate dynamic modelling. Substantial progresses have been made in the past on model development to provide better control strategy to ensure energy savings without sacrificing thermal comfort and indoor air quality in the Heating, Ventilation, and Air-conditioning systems. However, there are scarce model using the data driven approach in the Multi-circuit air-conditioning system. This research, carried out a study on the choice of a dynamic model for an operating centralized multi-circuit water-cooled package unit air-conditioning system using a system identification procedure. Baseline data were collected and analyzed, the model development was achieved by processing, estimating and validating the data in system identification. Result shows that the Autoregressive-moving average with exogenous terms (ARMAX) of the third order model, established the best model structure with the highest Best Fit and Lowest Mean Square Error.

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Dynamic simulation of indirect air conditioning systems with optimized computational time

E3S Web of Conferences ◽

10.1051/e3sconf/201911104042 ◽

2019 ◽

Vol 111 ◽

pp. 04042

Author(s):

Nicolás Ablanque ◽

Santiago Torras ◽

Carles Oliet ◽

Joaquim Rigola ◽

Carlos-David Pérez-Segarra

Keyword(s):

Air Conditioning ◽

Energy Savings ◽

Control Strategies ◽

Model Potential ◽

Hvac Systems ◽

Object Oriented Programming ◽

Computational Time ◽

Air Conditioning System ◽

Numerical Resolution ◽

Air Conditioning Systems

The simulation of HVAC systems is a powerful tool to improve the energy efficiency in buildings. The modelling of such systems faces several obstacles due to both the physical phenomenology present and the numerical resolution difficulties. The present work is an attempt to develop a robust, fast, and accurate model for HVAC systems that can interact with the other relevant systems involved in buildings thermal management. The whole system model has been developed in the form of libraries under the Modelica language to exploit its advantageous characteristics: object-oriented programming, equationbased modelling, and handling of multi-physics. The global resolution is carried out dynamically so that not only steady-state predictions can be conducted but also control strategies can be studied over meaningful periods of time. This latter aspect is crucial for optimizing energy savings. The libraries include models for all the system individual components such as pumps, compressors or heat exchangers (operating with twophase flows and/or moist air) and also models assemblies to account for vapour compression units and liquid circuits. An illustrative example of an indirect air conditioning system is detailed in the present work in order to highlight the model potential.

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OPTIMIZATION APPLIED TO ENERGY EFFICIENCY AND THERMAL COMFORT OF BUILDINGS: BIBLIOMETRIC ANALYSIS ON TECHNIQUES AND APPLICATIONS

Revista de Engenharia Térmica ◽

10.5380/reterm.v17i2.64126 ◽

2018 ◽

Vol 17 (2) ◽

pp. 20

Author(s):

C. F. da Silva ◽

R. Z. Freire ◽

N. Mendes

Keyword(s):

Energy Consumption ◽

Thermal Comfort ◽

Bibliometric Analysis ◽

Energy Demand ◽

Air Conditioning ◽

Energy Savings ◽

Control Strategies ◽

Building Projects ◽

Air Conditioning Systems ◽

And Control

The world's energy demand has raised concerns about supply difficulties, depletion of natural resources and environmental impacts such as destruction of ozone layer, global warming, climate change, among others. Recent studies indicate that energy consumption in buildings represents more than 40% of the world's energy consumption, with more than half of that attributed to air conditioning systems. Specific regulations and control strategies for heating, ventilation and air-conditioning (HVAC) systems should provide acceptable thermal comfort and reasonable indoor air quality. The evolution of researches in these areas can be evaluated by the organization of scientific production up to now. The objective of this study is to analyze quantitatively what was produced in terms of optimization associated to both energy savings and thermal comfort in buildings. This bibliometric analysis, based on Science Direct and IEEE Xplore databases, correlates common adopted terms to quantify how optimization, especially those associated to computational intelligence, are influencing building projects where thermal comfort and energy saving are taken into account. This research assumes a sample of 76 articles, and provided a statistical evaluation considering authors identification, and both articles and journals that were more cited by researchers in this area.

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Effect of Air Conditioning Position on Thermal Comfort in the Floor Air Conditioning System

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.493.74 ◽

2014 ◽

Vol 493 ◽

pp. 74-79

Author(s):

Y.A. Sabtalistia ◽

S.N.N. Ekasiwi ◽

B. Iskandriawan

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Energy Consumption ◽

Thermal Comfort ◽

Energy Efficient ◽

Air Conditioning ◽

Air Conditioning System ◽

Air Supply ◽

Air Conditioning Systems ◽

Air Diffusion

Energy consumption for air conditioning systems (air conditioning system) increased along with the increasing need for fresh air and comfortable in the room especially apartments. FAC system (Floor Air Conditioning) is growing because it is more energy efficient than CAC (Ceiling Air Conditioning) system. However, the position of the AC supply is on the lower level at the FAC system causes draft discomfort becomes greater as air supply closer to the occupants so that thermal comfort can be reduced. Heat mixture of windows, exterior walls, kitchen, and occupants in the studio apartment affect thermal comfort in the room too.This study aims to determine the position of the AC supply which has the best thermal comfort of FAC system in the studio apartment. It can be done by analyzing ADPI (Air Diffusion Performance Index), the distribution of air temperature, wind speed, RH (Relative Humidity), and DR (Draft Risk) to change the position of the AC supply supported by CFD (Computational Fluid Dynamics) simulation.This result prove that AC position 2 (on wall near the kitchen) is more comfortable than AC position 1 (on the bathroom wall) because AC position 2 away from occupied areas, thereby reducing the occurrence of draught discomfort.

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Thermal comfort control via air conditioning system using fuzzy neural network feedback controller

Indonesian Journal of Electrical Engineering and Computer Science ◽

10.11591/ijeecs.v19.i2.pp586-592 ◽

2020 ◽

Vol 19 (2) ◽

pp. 586

Author(s):

Somaye A. Mohamadi ◽

Abdulraheem J. Ahmed

Keyword(s):

Neural Network ◽

Thermal Comfort ◽

Environmental Conditions ◽

Air Conditioning ◽

Fuzzy Controller ◽

Environmental Parameters ◽

Thermal Conditions ◽

Real Time Control ◽

Air Conditioning System ◽

Air Conditioning Systems

<span>Despite their complexity and uncertainty, air conditioning systems should provide the optimal thermal conditions in a building. These controller systems should be adaptable to changes in environmental parameters. In most air conditioning systems, today, there are On/Off controllers or PID in more advanced types, which, due to different environmental conditions, are not optimal and cannot provide the optimal environmental conditions. Controlling thermal comfort of an air conditioning system requires estimation of thermal comfort index. In this study, fuzzy controller was used to provide thermal comfort in an air conditioning system, and neural network was used to estimate thermal comfort in the feedback path of the controller. Fuzzy controller has a good response given the non-linear features of air conditioning systems. In addition, the neural network makes it possible to use thermal comfort feedback in a real-time control.</span>

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A dynamic model for human thermal comfort for smart building applications

Proceedings of the Institution of Mechanical Engineers Part I Journal of Systems and Control Engineering ◽

10.1177/0959651819865795 ◽

2019 ◽

Vol 234 (4) ◽

pp. 472-483

Author(s):

Ghezlane Halhoul Merabet ◽

Mohamed Essaaidi ◽

Driss Benhaddou

Keyword(s):

Thermal Comfort ◽

Air Conditioning ◽

Research Work ◽

Comfort Level ◽

Indoor Environments ◽

Air Conditioning System ◽

Human Thermal Comfort ◽

Local Quality ◽

Set Up ◽

Air Conditioning Systems

Thermal comfort is closely related to the evaluation of heating, ventilation, and air conditioning systems. It can be seen as the result of the perception of the occupants of a given environment, and it is the product of the interaction of a number of personal and environmental factors. Otherwise, comfort issues still do not play an important role in the daily operation of commercial buildings. However, in the workplace, local quality effects, in addition to the health, the productivity that has a significant impact on the performance of the activities. In this regard, researchers have conducted, for decades, investigations related to thermal comfort and indoor environments, which includes developing models and indices through experimentations to establish standards to evaluate comfort and factors and set-up parameters for heating, ventilation, and air conditioning systems. However, to our best knowledge, most of the research work reported in the literature deals only with parameters that are not dynamically tracked. This work aims to propose a prototype for comfort measuring through a wireless sensor network and then presenting a model for thermal comfort prediction. The developed model can be used to set up a heating, ventilation, and air conditioning system to meet the expected comfort level. In particular, the obtained results show that there is a strong correlation between users’ comfort and variables such as age, gender, and body mass index as a function of height and weight.

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Hygrothermal study of dwelling submitted to passive cooling

Thermal Science ◽

10.2298/tsci160214289k ◽

2018 ◽

Vol 22 (6 Part A) ◽

pp. 2597-2604

Author(s):

Razika Kharchi ◽

Khaled Imessad

Keyword(s):

Relative Humidity ◽

Thermal Comfort ◽

Air Conditioning ◽

Natural Ventilation ◽

Energy Savings ◽

Pilot Project ◽

Passive Cooling ◽

Free Cooling ◽

Air Conditioning Systems ◽

Good Agreement

A significant portion of energy consumed in buildings is due to energy usage by heating, ventilation, and air conditioning systems. Free cooling is a good option for energy savings in the systems. In recent years, scientists, engineers, and architects designed successful and innovative buildings which use passive cooling techniques, such as natural ventilation. The house studied in the present work, is a pilot project undertaken jointly by the Centre for Development of Renewable Energies (CDER) and the National Centre for Studies and Research of the integrated building (CNERIB) in the framework of the MED-ENEC project (Mediterranean Energy Efficiency in Construction structure). The house under consideration has a surface area of 65 m2 and is located in the region of Algiers which characterized by a Mediterranean climate with relatively mild winters and a hot and humid summer. The aim of this work is to study the thermal comfort inside the house in summer without air conditioning systems, only ventilation is considered. The aim of this work is to study the effect of natural ventilation on both thermal and hygrometric comfort inside the house during the summer period. Numerical simulation is made using the TRNSYS software and the results obtained are in good agreement with measured values. The prototype home is designed in a way that natural ventilation allows thermal comfort which induced energy saving from air conditioning. The mean temperature measured in the interior of the house is 26?C. The relative humidity reaches about 70% in August. Thermal comfort is related to relative humidity that are the essential parameters of the feeling of comfort. Humidity is an important parameter in thermal comfort, it is why we can conclude that we have reached a relatively good hygrothermal comfort.

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Comfort as a Service: A New Paradigm for Residential Environmental Quality Control

Sustainability ◽

10.3390/su10093053 ◽

2018 ◽

Vol 10 (9) ◽

pp. 3053 ◽

Cited By ~ 5

Author(s):

Juan Gómez-Romero ◽

Miguel Molina-Solana ◽

María Ros ◽

M. Ruiz ◽

M. Martin-Bautista

Keyword(s):

Energy Supply ◽

Air Conditioning ◽

Ambient Intelligence ◽

Energy Savings ◽

Control Strategies ◽

External Factors ◽

New Paradigm ◽

Test Scenario ◽

Air Conditioning System ◽

New Energy

This paper introduces the concept of Comfort as a Service (CaaS), a new energy supply paradigm for providing comfort to residential customers. CaaS takes into account the available passive and active elements, the external factors that affect energy consumption and associated costs, and occupants’ behaviors to generate optimal control strategies for the domestic equipment automatically. As a consequence, it releases building occupants from operating the equipment, which gives rise to a disruption of the traditional model of paying per consumed energy in favor of a model of paying per provided comfort. In the paper, we envision a realization of CaaS based on several technologies such as ambient intelligence, big data, cloud computing and predictive computing. We discuss the opportunities and the barriers of CaaS-centered business and exemplify the potential of CaaS deployments by quantifying the expected energy savings achieved after limiting occupants’ control over the air conditioning system in a test scenario.

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Experimental Study and Analysis of Thermal Comfort in a University Campus Building in Tropical Climate

Sustainability ◽

10.3390/su12218886 ◽

2020 ◽

Vol 12 (21) ◽

pp. 8886

Author(s):

Milen Balbis-Morejón ◽

Javier M. Rey-Hernández ◽

Carlos Amaris-Castilla ◽

Eloy Velasco-Gómez ◽

Julio F. San José-Alonso ◽

...

Keyword(s):

Thermal Comfort ◽

Air Conditioning ◽

Thermal Environment ◽

Thermal Sensation ◽

Thermal Sensitivity ◽

Tropical Climate ◽

Air Conditioning System ◽

Humidity Measurements ◽

Air Conditioning Systems ◽

Thermal Preferences

This study presents the evaluation of the performance and acceptability of thermal comfort by students in the classrooms of a university building with minisplit-type air-conditioning systems, in a tropical climate. To carry out the study, temperature and humidity measurements were recorded, both outside and inside the selected classrooms, while the students were asked to complete thermal surveys on site. The survey model is based on the template proposed by Fanger and it was applied to a total number of 584 students. In each classroom, the Predicted Mean Vote (PMV) and the Predicted Percentage Dissatisfied (PPD) were estimated according to Fanger’s methodology, as well as the Thermal Sensation Vote (TSV) and the Actual Percentage Dissatisfied (APD), which were obtained from the measurements and the surveys. The results of this study showed that the PMV values, although they may vary with the insulation of the clothing, do not affect the TSV. Furthermore, comparing PMV vs. TSV scores, a 2 °C to 3 °C difference in operating temperature was found, whereby the thermal sensitivity for TSV was colder, so it could be assumed that the PMV model overestimates the thermal sensitivity of students in low-temperature conditions. In addition, an acceptability by 90% with thermal preferences between 23 °C and 24 °C were also found. These results indicate that it is possible to increase the temperature set point in minisplit-type air-conditioning system from 4 °C to 7 °C with respect to the currently set temperatures, without affecting the acceptability of the thermal environment to the students in the building.

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ANALYSIS OF COMPETING VARIANTS OF AIR CONDITIONING SYSTEMS WITHOUT AIR EXTRACTION FROM ENGINES AT THE STAGE OF PASSENGER AIRCRAFT ONBOARD SYSTEMS CONCEPTUAL DESIGN

Computational nanotechnology ◽

10.33693/2313-223x-2019-6-3-86-91 ◽

2019 ◽

Vol 6 (3) ◽

pp. 80-85

Author(s):

Denis Igorevich Smagin ◽

Konstantin Igorevich Starostin ◽

Roman Sergeevich Savelyev ◽

Anatoly Anatolyevich Satin ◽

Anastasiya Romanovna Neveshkina ◽

...

Keyword(s):

Conceptual Design ◽

Air Conditioning ◽

Research University ◽

Cooling System ◽

Fuel Efficiency ◽

Air Cooling ◽

Moscow Aviation Institute ◽

Air Conditioning System ◽

Low Efficiency ◽

Air Conditioning Systems

One of the ways to achieve safety and comfort is to improve on-board air conditioning systems.The use of air cooling machine determines the air pressure high level at the point of selection from the aircraft engine compressor. Because of the aircraft operation in different modes and especially in the modes of small gas engines, deliberately high stages of selection have to be used for ensuring proper operation of the refrigeration machine in the modes of the aircraft small gas engines. Into force of this, most modes of aircraft operation have to throttle the pressure of the selected stage of selection, which, together with the low efficiency of the air cycle cooling system, makes the currently used air conditioning systems energy inefficient.A key feature of the architecture without air extraction from the main engines compressors is the use of electric drive compressors as a source of compressed air.A comparative analysis of competing variants of on-board air conditioning system without air extraction from engines for longrange aircraft projects was performed at the Moscow Aviation Institute (National Research University).The article deals with the main approaches to the decision-making process on the appearance of a promising aircraft on-board air conditioning system at the stage of its conceptual design and formulated the basic requirements for the structure of a complex criterion at different life cycle stages.The level of technical and technological risk, together with a larger installation weight, will require significant costs for development, testing, debugging and subsequent implementation, but at the same time on-board air conditioning system scheme without air extraction from the engines will achieve a significant increase in fuel efficiency at the level of the entire aircraft.

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