Simulation Of Air Conditioning System Research Articles

Solar Air Conditioning Case Studies for Qatar Climate Conditions

Abstract Air conditioning (AC) is crucial for comfortable living in countries with challenging desert climates like Qatar. In the face of such harsh conditions, cooling applications account for up to 70% of energy consumption in residential buildings. Given the high-energy demand for cooling and the region's abundant solar resources, rooftop photovoltaics (PVs) can offer an ideal sustainable solution, as peak solar supply closely aligns with the electricity demand. This study aims to enhance the feasibility, effectiveness, and system design for solar ACs in Qatar's climate conditions. A simulation model is developed to evaluate different setups of solar AC systems, utilizing local historical weather data. Optimization strategies are explored and validated for the purpose of minimizing the need for costly battery storage. Results demonstrate the efficacy of these techniques, with potential reductions in battery capacity needs of up to 15% through heat inertia management and matching of energy supply and demand. The complete elimination of battery storage is found to be possible but would be at the expense of slight compromises in end-of-day indoor comfort, which can be addressed by cooling storage solutions.

Optimization Control Strategy for a Central Air Conditioning System Based on AFUCB-DQN

The central air conditioning system accounts for 50% of the building energy consumption, and the cold source system accounts for more than 60% of the total energy consumption of the central air conditioning system. Therefore, it is crucial to solve the optimal control strategy of the cold source system according to the cooling load demand, and adjust the operating parameters in time to achieve low energy consumption and high efficiency. Due to the complex and changeable characteristics of the central air conditioning system, it is often difficult to achieve ideal results using traditional control methods. In order to solve this problem, this study first coupled the building cooling load simulation environment and the cold source system simulation environment to build a central air conditioning system simulation environment. Secondly, noise interference was introduced to reduce the gap between the simulated environment and the actual environment, and improve the robustness of the environment. Finally, combined with deep reinforcement learning, an optimal control strategy for the central air conditioning system is proposed. Aiming at the simulation environment of the central air conditioning system, a new model-free algorithm is proposed, called the dominant function upper confidence bound deep Q-network (AFUCB-DQN). The algorithm combines the advantages of an advantage function and an upper confidence bound algorithm to balance the relationship between exploration and exploitation, so as to achieve a better control strategy search. Compared with the traditional deep Q-network (DQN) algorithm, double deep Q-network (DDQN) algorithm, and the distributed double deep Q-network (D3QN) algorithm, the AFUCB-DQN algorithm has more stable convergence, faster convergence speed, and higher reward. In this study, significant energy savings of 21.5%, 21.4%, and 22.3% were obtained by conducting experiments at indoor thermal comfort levels of 24 °C, 25 °C, and 26 °C in the summer.

A Study on the Application Possibility of the Vehicle Air Conditioning System Using Vortex Tube

Since refrigerants applied to vehicle air conditioning systems exacerbate global warming, many studies have been conducted to supplement them. However, most studies have attempted to maximize the efficiency and minimize the environmental impact of the refrigerant, and thus, an air conditioning system without refrigerant is required. The vortex tube is a temperature separation system capable of separating air at low and high temperatures using compressed air. When applied to an air conditioning system, it is possible to construct an eco-friendly system that does not use a refrigerant. In this paper, various temperature changes and characteristics of a vortex tube were identified and applied to an air conditioning system simulation device. Additionally, an air conditioning system simulation device using indirect heat exchange and direct heat exchange methods was constructed to test the low-temperature air flow rate (yc), according to the temperature and pressure. As a result of the experiment, the temperature of the indirect heat exchange method was found to be higher than the direct heat exchange method, but the direct heat exchange method had low flow resistance. As a result, the direct heat exchange method can easily control the temperature according to the pressure and the low-temperature air flow rate (yc). Therefore, it was judged that the direct heat exchange method is more feasible for use in air conditioning systems than the indirect heat exchange method.

Design and Simulation of Air Conditioning System in a Large Auditorium Based on Computational Fluid Dynamics

Air conditioning system is an indispensable part of buildings today. The cost of this system increases with the rise in energy consumption which poses a challenge as well as air distribution in large auditoria. Analysis of results can also be daunting when designing this system. The study focuses on designing an air conditioning system in a large auditorium, applying Computational Fluid Dynamics (CFD) and visualizing the result in a Virtual Reality (VR) environment. The 3-dimensional model of the 520-capacity Technology Lecture Theatre, University of Ibadan, Nigeria was drawn with Autodesk Revit and modified into the geometry applicable for Displacement Ventilation (DV) and Mixed Ventilation (MV) for ease of numerical analysis with ANSYS Fluent. The building model and simulation results were then imported into Unity software for visualization in VR. The DV achieved better thermal comfort and air distribution in the computer simulation. At a supply temperature of 292.15 K, the DV system was able to keep the auditorium temperature at about 296.50 K, while the MV system at a supply temperature of 289.15 K was only able to maintain the temperature at 295.40 K. The temperature profile showed that the lower region where the students were seated was colder in DV compared to MV by at least 3 K. The results were also observed from a convenient position in VR. This study, with the aid of CFD and VR, was able to establish that displacement ventilation design has better air flow, lower energy consumption and is efficient for an air conditioning system in a large auditorium.

Design and Simulation of Air Conditioning System in a Large Auditorium Based on Computational Fluid Dynamics

Air conditioning system is an indispensable part of buildings today. The cost of this system increases with the rise in energy consumption which poses a challenge as well as air distribution in large auditoria. Analysis of results can also be daunting when designing this system. The study focuses on designing an air conditioning system in a large auditorium, applying Computational Fluid Dynamics (CFD) and visualizing the result in a Virtual Reality (VR) environment. The 3-dimensional model of the 520-capacity Technology Lecture Theatre, University of Ibadan, Nigeria was drawn with Autodesk Revit and modified into the geometry applicable for Displacement Ventilation (DV) and Mixed Ventilation (MV) for ease of numerical analysis with ANSYS Fluent. The building model and simulation results were then imported into Unity software for visualization in VR. The DV achieved better thermal comfort and air distribution in the computer simulation. At a supply temperature of 292.15 K, the DV system was able to keep the auditorium temperature at about 296.50 K, while the MV system at a supply temperature of 289.15 K was only able to maintain the temperature at 295.40 K. The temperature profile showed that the lower region where the students were seated was colder in DV compared to MV by at least 3 K. The results were also observed from a convenient position in VR. This study, with the aid of CFD and VR, was able to establish that displacement ventilation design has better air flow, lower energy consumption and is efficient for an air conditioning system in a large auditorium.

Simulation of the Thermal Environment and Velocity Distribution in a Lecture Hall

The rational design of heating ventilation and air conditioning systems is an important means to achieve energy conservation and sustainable development. The simulation of air-conditioning systems with finite element methods has gradually become an important auxiliary means of complex airspace design. In this paper, a k-ε turbulence model is used to conduct 3D simulations and optimize the summer air conditioning system of a lecture hall. Various conditions are considered in terms of fresh air temperature and flow rate towards the end to improve comfort. The approach used in this paper could also be used in the future as an auxiliary model to promote the design of other lecture halls and ladder classrooms.

CFD Simulation of Air Conditioning System of the Classroom

CFD Simulation of Air Conditioning System of the Classroom

Utilization of Solar Energy for Air Conditioning System

The purposes of this research are to do a system simulation of air conditioning utilizing solar energy with single effect absorption refrigeration method, analyze the coefficient of performance (COP) for each absorbent-refrigerant variable and compare the effectivity of every absorbent-refrigerant variable used. COP is a constant that denotes the effeciency of a refrigeration system, that is ratio of work or useful output to the amount of work or energy input. The higher the number of COP, the more efficient the system is. Absorbent-refrigerant (working fluids) variables used in this research depend on its chemical and thermodynamics properties. Steps in this research are including data collection and tabulation from literature and do a simulation of air conditioning system both commercial air conditioning system (using electrical energy) and solar energy air conditioning system with Aspen Plus software. Next, run the simulation for each working fluid variables used and calculate the COP for each variable. Subsequently, analyze and compare the effectivity of all variables used from COP value and economical point of view with commercial air conditioning system. From the result of the simulation, can be concluded that solar air conditioning can achieve 98,85 % of energy savings than commercial air conditioning. Furthermore, from the calculation of COP, the highest COP value is achieved by solar conditioning system with LiNO3-NH3 as working fluid where 55% of the composition is the refrigerant and 45% of absorbent.

Surface Water Source Heat Pump Air Conditioning System Simulation and Operation Performance Analysis

Abstract This paper established a heat pump system model containing heat pump unit model, AC load model and heat exchanger model utilizing the mass and energy balance and the structure's designing method. This paper also developed the surface water source heat pump air conditioning system simulation program by Visual Basic, and verified the simulation by the actual engineering project. In addition, this paper explored the impact of the surface water temperature and heat exchanger structure on the heat pump air conditioning system operation. The results shows that one degree drop of the surface water temperature leads to 2.3 per cent increase of performance coefficient and a 100m added length of the closed-loop surface water heat exchanger tube leads to 0.08 per cent increase of performance coefficient.

Optimal Collector Type and Temperature in a Solar Organic Rankine Cycle System for Building-Scale Power Generation in Hot and Humid Climate

The objective of this paper is to determine the optimal solar collector type and temperature of a building-scale power generation system employing solar organic Rankine cycle (ORC) engine for a geothermal air-conditioned net zero-energy building (NZEB) in a hot and humid climate. In the authors' previous work, 11 fluids have been suggested to be employed in solar ORCs that use low-temperature or medium-temperature solar collectors. In this paper, the system requirements needed to maintain the electricity demand of a commercial building have been compared for the 11 suggested fluids. The solar collector loop, building, and geothermal air conditioning system are modeled using TRNSYS with the required input for the ORC system derived from the previous study. The commercial building is located in Pensacola of Florida and is served by grid power. The building has been equipped with two geothermal heat pump units and a vertical closed loop system. The performance of the geothermal system has been monitored for 3 weeks. Monitoring data and available electricity bills of the building have been employed to calibrate the building and geothermal air conditioning system simulation. Simulation has been repeated for Miami and Houston in order to evaluate the effect of the different solar radiations on the system requirements.

B-15 室内気流連成型動的空調システムシミュレーションに関する研究 : 第1報:動的空調システムシミュレーションの意義と現状の問題点

B-15 室内気流連成型動的空調システムシミュレーションに関する研究 : 第1報:動的空調システムシミュレーションの意義と現状の問題点

Heating, ventilation and air conditioning system modelling

Abstract Heating, ventilation and air conditioning modelling methods, for large scale, spatially dispersed systems are considered. Existing techniques are discussed and proposals for the application of novel analysis approaches are outlined. The use of distributed–lumped parameter procedures enabling the incorporation of the relatively concentrated and significantly dispersed, system element characteristics, is advocated. A dynamic model for a heating, ventilation and air conditioning system comprising inlet and exhaust fans, with air recirculation, heating/cooling and filtration units is presented. Pressure, airflow and temperature predictions within the system are computed following input, disturbance changes and purging operations. The generalised modelling advancements adopted and the applicability of the model for heating, ventilation and air conditioning system simulation, re-configuration and diagnostics is emphasised. The employment of the model for automatic, multivariable controller design purposes is commented upon.

B-5 熱源システムの相違による最適化シミュレーションの開発

B-5 熱源システムの相違による最適化シミュレーションの開発

THE COMPARATIVE STUDY OF THE AIR-CONDITIONING SYSTEM SIMULATION TOOL

From the viewpoint of indoor environmental control and CO2 discharge reduction, it’s necessary to evaluate the air-conditioning system in life cycle. And the system simulation is effective for evaluating an air-conditioning system. We compared “DeST” with “LCEM tool”, which are the air-conditioning system simulation program, in the characteristic, calculation algorithm, function and result of simulation for the model building. They have some difference of handling components and the calculation algorithm. However, we showed we can get almost same result when we adjust points that we can.

A development of easy-to-use tool for fault detection and diagnosis in building air-conditioning systems

There are many reports about faulty status in building air-conditioning systems recently. It becomes difficult to keep indoor air temperature appropriately as faults occur, and the faults cause waste of building energy consumption. The model-based fault detection and diagnosis (FDD) methods have been researched for specific parts of air-conditioning system such as chillers, coils, variable air volume units (VAV units), etc. It needs, however, much time and labor to monitor and check every single part because we cannot predict where and when the faults occur. The purpose of this study is to examine indoor air temperature changes and energy consumption increase when faults occur and to develop an easy-to-use FDD tool that helps to find out the faulty place through the whole building air-conditioning system. And then, we treat the reliability of the proposed FDD tool and effectiveness to control of indoor environment deterioration and energy consumption increase by the tool is evaluated based on building air-conditioning system simulation in this paper.

Refrigerant Flow Through Flexible Short-Tube Orifices

Flexible short-tube orifices were designed to decrease their diameter as the pressure differential across them increases under high outdoor temperatures. A series of tests for an R-22/lubricant mixture (mass fraction of oil 1.2%) were performed with two flexible short-tube orifices to develop flow data over a range of typical air conditioner operating conditions. One short tube had a modulus of elasticity of 7063 kPa and the other a value of 9860 kPa. Both short tubes had identical lengths (14.5 mm), entrance diameters (2.06 mm), and exit diameters (2.46 mm). The tests included both single- and two-phase flow conditions at the inlet of the flexible short tube. Upstream pressures were varied from 1179 kPa to 2144 kPa, which corresponded to saturated condensing temperatures of 29.4 to 54.4°C. Experimental results were presented as a function of pressure, subcooling/quality, evaporating pressure, and modulus of elasticity. Mass flow rates were compared with those of a rigid short tube. The flow rate through the flexible short-tube orifices was strongly dependent on the condensing pressure, subcooling/quality, and modulus of elasticity (which, in effect, changed diameter at different upstream pressures) of the short-tube material. However, the flow rate showed little dependence on the evaporating pressure. An empirical flow model was developed using the experimental data. This flow model was then combined with an air-conditioning system simulation model. Results from the model indicated that the flexible short tube provided approximately 2 to 3% higher capacity than the fixed expansion devices at temperatures lower than 25°C and higher than 45°C. However, the flow control with the flexible short-tube orifice was not as good as with a thermal expansion valve.

Problems and method of simulation of air conditioning systems of civil aviation aeroplanes

Analyzed ate the existing mathematical methods and models which are connected with computerized simulation of engineering thermal network. Determined are the basical principles of decomposition and technology of development of computer means of simulation of aviation air conditioning system

Real Time Simulation of On-Line BMS and Air-Conditioning System for Training/Learning Applications

A PC-based software, BMSonline, is developed to simulate a ’on-line’ IEArning environment of BMS by simulating the BMS on-line DDC controls and supervisory strategies, the thermal, hydraulic and environmental characteristics and energy performance of a building and VAV air conditioning system. A window-based user interface is developed for the users to monitor the online operation, to tune the DDC control loops and to modify the supervisory control strategies on-line and off-line. This paper presents the real-time simulation of the air-conditioning system and the BMS on-line controls, the user interface and examples for the users to practise and test the dynamic performance of BMS controls and air-conditioning system on the software.

Chiller models for plant design studies

Numerical models for air- and water-cooled centrifugal, reciprocating and screw chillers are presented. The models were established by curve-fitting manufacturers' chiller performance data. They relate the electricity demand of a chiller to its cooling output and to the temperature of the condenser inlet cooling medium. Including the cooling medium temperature as an independent variable in the model allows its effect on chiller performance to be accounted for explicitly. This contrasts with relying on an assumed relationship between this temperature and the chiller load (e.g. according to the ARI Standard rating conditions). Using chiller models based on such an assumption can lead to erroneous energy use predictions for chiller plants comprising multiple chillers. Predictions of the chiller models agreed reasonably well with chiller performance data extracted from reocrds of plant operation. The models have been incorporated into an air-conditioning system simulation program BECON as its built-in chiller model. A simulation study aimed at comparing the performance of alternative chiller number-size combinations for a building is described. This shows that such studies should be based on realistic rated COP values for chillers, as they will strongly influence the predicted electricity consumption and thus the conclusion on which combination is to be adopted.

Air Conditioning System Simulation for Rooms and Duct System

Air Conditioning System Simulation for Rooms and Duct System