Managing the energy of the air conditioning systems using a modified multi-variable control technique

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
K.M.K. Pasha
Keyword(s):  
Sampling Interval ◽  
Control Technique ◽  
Opening Angle ◽  
Time Intervals ◽  
Air Conditioners ◽  
First Case ◽  
Commercial Code ◽  
Suggested Technique ◽  
Mimo Control ◽  
Air Conditioning Systems

This research is a continuation of our previous work [19], in which, I’ve investigated many control techniques for the multi-input multi-output (MIMO) control systems for air conditioners. In the present work, I’ve suggested another control technique which exhibited better performance in the cases where permanent disturbances are present. I’ve applied the technique to a model room that simulates a computer room and is conditioned by a simple, less expensive, and energy-saver HVAC system. The two control inputs are; the opening angle of a fresh air gate and the steam flow rate from a humidifier. The two controlled outputs are the temperature and humidity. The control technique and the in-door conditions are simulated using a written program that works along with a commercial code. The sampling interval for each controlled variable is modified to allow more accuracy for measured data. When applying accidental and permanent disturbances in both controlled variables, the suggested technique exhibited accepted performance. The controlled variables that are affected with permanent disturbances achieved their set-point values after longer time intervals than those of the cases where only accidental disturbances are present. Two comparisons were made between the controlled and uncontrolled system by operating the system for a certain period, and fixing the fresh air opening at 25% and 50% of the full opening area. The consumed energy in the two cases was compared with that of the case when applying the control technique for the same period. An energy-saving of about 15.3% was recorded in the first case and about 37.6% for the second case. The present technique is a case-independent and may be applied to any MIMO control system with little modifications.

A Semantic Differential for Evaluating the Sound Quality of Fan Systems

2017 ◽  
Author(s):  
Carolin Feldmann ◽  
Thomas Carolus ◽  
Marc Schneider
Keyword(s):  
Principal Component ◽  
Semantic Differential ◽  
Sound Quality ◽  
Heat Pumps ◽  
First Case ◽  
Objective Metrics ◽  
Main Components ◽  
Air Conditioning Systems ◽  
The University

Fans are main components e.g. in heating, ventilating and air conditioning systems for vehicles or buildings, cooling units of engines and electronic circuits, and household appliances such as kitchen exhaust hoods or vacuum cleaners. End-users increasingly demand a high sound quality of their system or device. The overall objective of a recent research project at the University of Siegen is a multidimensional assessment of fan sound quality. In a first step an advanced novel semantic differential for the assessment of fan-related sounds is established with the aid of carefully designed jury tests. Eventually, this semantic differential is employed for sound quality jury tests of fans in kitchen exhaust hoods, heat pumps and air purifiers as a first case. Finally, a prediction model is suggested, which relates the outcome from the jury tests to objective metrics. A principal component analysis is carried out and yields five main assessment criteria with 23 relevant adjective scales. The results show that the perceived sound quality of fan systems is mainly determined by the loudness and tonality of the sound. The spectral content (represented by the sharpness) as well as the time structure (represented by the roughness) have no significant impact on perceived sound quality of the fan systems investigated.

Experimental Investigation of a Desiccant Wheel Cycle

2012 ◽  
Author(s):  
Ali Al-Alili ◽  
Yunho Hwang ◽  
Reinhard Radermacher
Keyword(s):  
Air Conditioning ◽  
Removal Rate ◽  
Dew Point ◽  
Coefficient Of Performance ◽  
Cycle Performance ◽  
Air Conditioners ◽  
Considerable Portion ◽  
Temperature Heat ◽  
Air Conditioning Systems ◽  
Desiccant Material

In hot and humid regions, removal of moisture from the air represents a considerable portion of the air conditioning load. Conventionally, air conditioning systems have to lower the air temperature below its dew point to accomplish dehumidification. Desiccant air conditioners offer a solution to meet the humidity and temperature requirements of buildings via decoupling latent and sensible loads. In this work, the performance of a new desiccant material is investigated experimentally. This desiccant material can be regenerated using a low temperature heat source, as low as 45°C. It also has a unique S-shape isotherm. The effects of the process air stream’s temperature and humidity, the regeneration temperature, the ventilation mass flow rate, and the desiccant wheel’s rotational speed on the cycle performance are investigated. ARI-humid conditions are used as a baseline and the moisture mass balance is maintained within 5%. The results are presented in terms of the moisture removal rate and latent coefficient of performance (COPlat). The results show a desiccant wheel’s COPlat higher than unity when it is coupled with an enthalpy wheel.

Identification of spontaneous cardiac baroreflex episodes at different timescales in rats

1998 ◽  
Vol 274 (2) ◽  
pp. H488-H493 ◽  
Author(s):  
Marie-Paule Gustin ◽  
Catherine Cerutti ◽  
Robert Unterreiner ◽  
Christian Paultre
Keyword(s):  
Heart Rate ◽  
Sampling Interval ◽  
Statistical Relationship ◽  
Sprague Dawley ◽  
Time Intervals ◽  
Sprague Dawley Rats ◽  
Low Pass ◽  
Freely Moving ◽  
Spontaneous Baroreflex ◽  
Long Timescales

To study spontaneous cardiac baroreflex at different timescales, a new method has been developed that identifies such episodes. Mean arterial pressure (MAP) and heart rate (HR) were recorded beat to beat over 1 h in freely moving control ( n = 10) and acutely (1 day before study, n = 7) and chronically (2 wk before study, n = 10) sinoaortic-denervated (SAD) 12- to 14-wk-old male Sprague-Dawley rats. These beat-to-beat time series were successively low-pass filtered seven times and resampled at different time intervals from 0.1 to 6.4 s, allowing different timescales to be scanned. With the use of the Z coefficient, the statistical relationship was estimated for the associations of inverse MAP and HR variations when these inverse MAP and HR variations occurred simultaneously or were time shifted. In control rats and for timescales ≥0.4 s, the highest Zcoefficient(0.38) was obtained when MAP variations preceded inverse HR variations by one sampling interval. The baroreflex origin of this link was demonstrated by its disappearance after acute SAD. In conclusion, this method enabled spontaneous baroreflex episodes to be identified for unusually long timescales without limiting the study to fast, linear, stationary, or oscillating phenomena.

Analysis and Design of Efficient Absorbers for Low-Temperature Desiccant Air Conditioners

1981 ◽  
Vol 103 (1) ◽  
pp. 67-74 ◽  
Author(s):  
C. S. P. Peng ◽  
J. R. Howell
Keyword(s):  
Mass Transfer ◽  
Low Temperature ◽  
Heat And Mass Transfer ◽  
Mass Transfer Rate ◽  
Falling Film ◽  
Air Conditioners ◽  
Tube Heat Exchanger ◽  
Analysis And Design ◽  
Fin Tube ◽  
Air Conditioning Systems

Desiccant dehumidification and air-conditioning systems require careful design to minimize large parasitic power requirements for pumps and blowers. Each component depends to some extent on overall system characteristics, yet each component must be carefully modeled in itself. The most challenging part of optimizing a system is the absorber design. In order to increase the heat and mass transfer rate while minimizing the pressure loss in the absorber, a direct contact falling film fin-tube heat exchanger is analyzed with water flowing on the tube side and desiccant flowing as a falling film on the fin side. Air is cooled and dehumidified by the water and desiccant as it is circulated through the absorber. A model to analyze the heat and mass transfer in the absorber has been developed. An optimum design has been selected based on not only thermal performance but also practical and economic considerations. Application of the absorber design is then made to design of a complete desiccant system for use with low-temperature heat as an energy source.

scholarly journals Distributed Attitude Consensus for Multiple Rigid Spacecraft under Jointly Connected Switching Topologies

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Long Ma ◽  
Shicheng Wang ◽  
Haibo Min ◽  
Shouyi Liao ◽  
Zhiguo Liu
Keyword(s):  
Function Method ◽  
Consensus Problem ◽  
Time Intervals ◽  
Common Lyapunov Function ◽  
Switching Topologies ◽  
First Case ◽  
Lyapunov Function Method ◽  
Communication Topology ◽  
Leader Following ◽  
Rigid Spacecraft

We study the distributed leader-following attitude consensus problem for multiple rigid spacecraft with a single leader under jointly connected switching topologies. Two cases are considered, where the first case is with a static leader and the second case is with a dynamic leader. By constructing an auxiliary vector and a distributed observer for each follower spacecraft, the controllers are designed to drive all the attitudes of the follower spacecraft to the leader’s, respectively, for both of the two cases, though there are some time intervals in which the communication topology is not connected. The whole system is proved to be stable by using common Lyapunov function method. Finally, the theoretical result is illustrated by numerical simulations.

scholarly journals Method for consolidate representation of fossil objects dating

2020 ◽  
pp. 150-158
Author(s):  
D.I. Yakushev
Keyword(s):  
Moisture Content ◽  
Sampling Interval ◽  
Simple Rule ◽  
The Internet ◽  
Fourth Stage ◽  
Time Intervals ◽  
Second Stage ◽  
The Third ◽  
Dating Methods ◽  
Third Stage

So far, methods of dating fossil objects have allowed us to obtain a large amount of data that characterize the moisturization of our planet’s areas during different time intervals. At the same time, in some cases, fossil objects contain information about the characteristics of the climate of the epoch of their existence. The available dating is scattered and does not allow us to get an overall picture of the changes occurred. Therefore, the developed method of aggregate representation of dates is relevant. Scientific materials containing the desired dating are mainly presented on the Internet. Therefore, the target of the first stage is to identify the publications of interest. At the second stage, the dating found and its characteristics are summarized in table 1. At the third stage, the data in table 1 is converted to table 2, reflecting the change in the moisture content of regions with a 100 years sampling interval. At the fourth stage, a simple rule is applied to exclude two multidirectional trends in each cell of table 2. As a result of exclusion, only unidirectional signs remain in each cell that qualitatively characterize the moisture content of the studied regions. It seems that the dating found in a significant minority should be questioned. However, cases in which the number of exceptions exceeds the number of non-excluded characters require additional research. The proposed method is not limited either by the number of studies involved or by the dating methods used. The scientific novelty of the proposed method consists in the aggregate representation of known dating of fossil objects containing information about the characteristics of the climate of the epoch of its existence. The objectivity of the results obtained is based on the use of a variety of independent dating of fossil objects obtained by different methods for different periods and regions. The reliability of the results obtained will increase with the number of dating involved in the analysis.

scholarly journals Validation of An Instrument to Know the Use of Smart Devices in Air Conditioners and Their Improvement in Energy Efficiency: Case Study in Ecuador

2021 ◽  
Vol 17 (04) ◽  
pp. 133
Author(s):  
Jorge Israel Anchundia-Santana ◽  
Julieta Evangelina Sánchez-Cano ◽  
Washington Garcia-Quilachamin ◽  
Evelyn Isabel Santana-Mantuano
Keyword(s):  
Energy Efficiency ◽  
Air Conditioning ◽  
Fossil Fuels ◽  
Online Survey ◽  
Smart Devices ◽  
Air Conditioners ◽  
Industrial Sectors ◽  
The Republic ◽  
Air Conditioning Systems

The constant growth of the world’s population has generated various changes in the use of the diversity of the resources provided to us by the planet. Considering that by properly managing energy in air conditioning systems correctly, it collaborates in the fight against climate change, reducing the excessive use of fossil fuels and, therefore, the emission of CO2 and other greenhouse gases, creating an environment of comfort in industrial sectors, businesses, companies, homes, among others. The objective of this research is to validate the instrument considering the information obtained about smart devices applied in air conditioning systems and their improvement in energy efficiency. The methodology applied consisted of a field study conducted through an online survey that was directed at 226 students and professionals from three provinces of the Republic of Ecuador. To validate the data obtained in the instrument, the exploratory factor analysis was performed also of the principal components in the last phase it was obtained in factor transformation matrix (0.986), which demonstrates the validity of the study. To apply the KMO test and Bartlett’s sphericity, the following ranges (≥0.6) y (<0.05) were considered respectively.

scholarly journals Solar hybrid air conditioning system to use in Iraq to save energy

2019 ◽  
Vol 124 ◽  
pp. 01024
Author(s):  
Y. V. Vankov ◽  
A. K. Al–Okbi ◽  
M. H. Hasanen
Keyword(s):  
Air Conditioning ◽  
Power Plants ◽  
Cooling System ◽  
Renewable Energy Sources ◽  
Electricity Consumption ◽  
Air Conditioners ◽  
Reduce Electricity Consumption ◽  
Central Air Conditioning ◽  
Save Energy ◽  
Air Conditioning Systems

The energy saving issues are becoming necessary worldwide, as excessive consumption of energy leads to the consumption of a larger amount of fuel, increases environmental pollution and negatively affects the ozone layer. In Iraq, in particular, the demand for central air conditioning systems and home air conditioners with high electrical capacity has become increasingly clear in the recent years. Air conditioning systems within residential and public buildings, as well as government facilities became a necessity for good internal comfort, which was driven by desertification, high temperature, air pollution and increased population, resulting in increased consumption of electric power and pressing of power plants. Aiming at usage of renewable energy sources, the proposed system uses solar collectors as auxiliary solar thermal compressors and integrate them with air conditioning systems. The proposed solution will increase the cooling system efficiency, reduce electricity consumption and pollution.

Development of Heating and Cooling Local Air Conditioning System for Houses

2018 ◽  
Vol 931 ◽  
pp. 920-925
Author(s):  
Zohrab Melikyan ◽  
Naira Egnatosyan ◽  
Siranush Egnatosyan
Keyword(s):  
Air Conditioning ◽  
Point Of View ◽  
Air Conditioner ◽  
Air Conditioning System ◽  
Air Conditioners ◽  
Heating And Cooling ◽  
The Creation ◽  
Air Conditioning Systems

Centralized air conditioning systems are widely used in buildings at present. In these conditioners, the outside air gets required temperature, humidity, purity, and other features, necessary for creating comfort microclimate in inside areas of houses, and by the help of fans and air ducts the processed air moves to all rooms of a building. As a result, the creation and maintenance of comfort conditions in buildings become complicated and expensive activity. From this point of view, it is becoming more expedient to install local air conditioners in each room instead of single central one for the whole building. For this reason new local air conditioner is developed.

scholarly journals Use of condensed water from air conditioning systems

2018 ◽  
Vol 8 (1) ◽  
pp. 284-292
Author(s):  
Paulo Sergio Scalize ◽  
Samara Silva Soares ◽  
Andreia Cristina Fonseca Alves ◽  
Thaynara Azevedo Marques ◽  
Gabriel Gade Martins Mesquita ◽  
...  
Keyword(s):  
Water Quality ◽  
Environmental Sustainability ◽  
Water Conservation ◽  
Air Conditioning ◽  
Heterotrophic Bacteria ◽  
Quality Parameters ◽  
Daily Consumption ◽  
Air Conditioners ◽  
Condensed Water ◽  
Air Conditioning Systems

Abstract Facing the growing demand for water, discussions on environmental sustainability and conservation of this resource have become increasingly important. Among the possibilities for water conservation, air conditioning systems have potential applicability because, during their operation, water is generated via the condensation of air humidity, which is normally discarded. Thus, the objective of this work was to evaluate the water released by air conditioning equipment (condensed water) installed in the Laboratory of Water Analysis (LAnA) qualitatively and quantitatively, in order to verify its potential for use in the laboratory itself. For this, the quality of the water produced by three air conditioners was compared water quality parameters found in the literature, as well as with water produced by a distiller and an ultra-purifier, both used in the LAnA. Water quality was evaluated using physicochemical parameters (i.e. pH, electrical conductivity, resistivity, alkalinity, turbidity, apparent color and hardness) and microbiological parameters (i.e. total coliforms, Escherichia coli and heterotrophic bacteria). The average water flow produced by the three monitored air conditioners was 3.08 L/hour, which is higher than the daily consumption by the LAnA, indicating that its use would be quantitatively propitious. The physicochemical and microbiological analyses found that, condensed water can be used in the routine activities of LAnA. However, for its use as reagent-grade water, a prior treatment would be necessary, mainly due to the presence of heterotrophic bacteria.

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