The Noise Produced by the Air Handling Units Depending on the Type of Engine

2017 ◽  
Author(s):  
Sebastian Jachimowicz ◽  
Katarzyna Gładyszewska-Fiedoruk
Keyword(s):  
Ventilation System ◽  
Sound Level ◽  
Design Parameters ◽  
Direct Drive ◽  
Worst Case ◽  
Air Handling Unit ◽  
Air Handling Units ◽  
Negative Effect ◽  
Air Ventilation ◽  
The Difference

The elaboration is the study is to examine the difference in the sound level in the air handling units made by the same producer. These units are of the same design parameters and components, and supply air and exhaust air. The only difference is mounted engines. Tested air handling units are equipped with an engine type EC, and traditional direct drive, controlled by an converter. Sound level measurements were carried out in the ducts supply air ventilation system at a distance of 1 m from the air handling unit and for the unit at a distance of 2 m from the inspection door of the fan section of the supply, with 3 settings efficiency of units 30%, 60% and 90%. Tested headquarters are located inside the building. Excessive noise has a negative effect on the human body, resulting in fatigue, difficulty in learning and concentration, impaired orientation, annoyance, increase in blood pressure, headaches, dizziness, and in the worst case of temporary or permanent hearing loss. For this reason it is very important to protect against noise. Therefore, it was these studies.

scholarly journals Analysis of heat exchanger in an air handling unit – A case study

2021 ◽  
Vol 321 ◽  
pp. 04018
Author(s):  
Marek Borowski ◽  
Klaudia Zwolińska ◽  
Marcin Czerwiński
Keyword(s):  
Energy Demand ◽  
Ventilation System ◽  
Temperature Changes ◽  
Air Handling Unit ◽  
Air Handling Units ◽  
External Conditions ◽  
Energy Consuming ◽  
Actual Operation ◽  
The Subject

Ventilation plays an important role in providing comfortable conditions for users and is also one of the most energy-consuming systems in the building. Due to successive regulations aimed at reducing the energy load of buildings towards zero-energy buildings, energy recovery systems in air handling units have become an indispensable element. The high effectiveness of the entire system guarantees a reduction in energy demand. At very low or very high external temperatures, appropriate comfort conditions are provided by additional heaters or coolers. The subject of the paper is a ventilation system in a hotel located in southern Poland. The building is a faithful reconstruction of the historical saltworks adapted for the needs of the hotel. The air handling unit equipped with a rotary exchanger supplies air to hotel rooms located on two floors. The analysis includes the effectiveness of the air-handling unit operation under various external conditions, as well as the temperature changes during heat exchange. The results show the actual operation of the air-handling unit, which is particularly important in terms of reducing the energy consumption of the hotel.

Comparing Cooling Energy between Existing Air-Conditioning System and Proposed Design System

2014 ◽  
Vol 699 ◽  
pp. 834-839
Author(s):  
M.M. Syafiq Syazwan ◽  
M.Z.M. Yusof ◽  
C.K. Chang ◽  
M.D. Amir Abdullah
Keyword(s):  
Air Conditioning ◽  
Cooling Capacity ◽  
Design System ◽  
Air Conditioning System ◽  
Air Handling Unit ◽  
Standard Operation ◽  
Air Ventilation ◽  
The Difference ◽  
Heat Loads ◽  
Psychrometric Chart

Air-conditioning (AC) system is typically used to remove the sensible and latent heat loads in buildings. It provides cool and dehumidified air to meet the occupants comfort and good indoor air quality (IAQ). Improper design and analysis of AC process resulted in high cooling energy and unsatisfied indoor humidity level in tropical climate. The objective of this study is to identify the cooling energy in hotel restaurant by comparing the design with proper fresh air ventilation design. The hotel restaurant was designed with primary air unit (PAU) and air handling unit (AHU) as to remove sensible and latent loads. The performance of the AC system has been monitored and analysed using psychrometric chart. For the AC air side system, 296.2 kW of cooling energy was used in standard operation. An alternative design was proposed for the said hotel restaurant employing only one AHU, with a cooling capacity of 165.9 kW which was 43 % lower than the existing system. The difference in temperature, humidity ratio and air flow rate influenced the cooling energy for AC system.

Automated Proactive Techniques for Commissioning Air-Handling Units

2003 ◽  
Vol 125 (3) ◽  
pp. 282-291 ◽  
Author(s):  
Srinivas Katipamula ◽  
Michael R. Brambley ◽  
Larry Luskay
Keyword(s):  
Diagnostic Tools ◽  
Control Algorithms ◽  
Outdoor Air ◽  
Air Handling Unit ◽  
Long Run ◽  
Air Handling Units ◽  
Air Ventilation ◽  
The Cost ◽  
Diagnostic Technologies ◽  
Ventilation Systems

Lack of or improper commissioning, the inability of the building operators to grasp the complexity controls, and lack of proper maintenance lead to inefficient operations and reduced lifetimes of equipment. If regularly scheduled manual maintenance or re-commissioning practices are adopted, they can be expensive and time consuming. Automated proactive commissioning and diagnostic technologies applied to parts of the commissioning process address two of the main barriers to commissioning: cost and schedules. Automated proactive commissioning and diagnostic tools can reduce both the cost and time associated with commissioning, as well as enhance the persistence of commissioning fixes. In the long run, automation even offers the potential for automatically correcting problems by reconfiguring controls or changing control algorithms dynamically. This paper discusses procedures and processes that can be used to automate and continuously commission the economizer operation and outdoor-air ventilation systems of an air-handling unit.

Comparison of two air sampling methods to monitor operating room air quality and assessment of air quality in two operating rooms with different ventilation systems in the national hospital of Sri Lanka

2016 ◽  
Vol 12 (3) ◽  
Author(s):  
Tshokey Tshokey ◽  
Pranitha Somaratne ◽  
Suneth Agampodi
Keyword(s):  
Air Quality ◽  
Sri Lanka ◽  
Operating Room ◽  
Ventilation System ◽  
Surgical Site Infections ◽  
National Hospital ◽  
Air Contamination ◽  
Acceptable Method ◽  
The Difference ◽  
Laminar Air Flow

Air contamination in the operating room (OR) is an important contributor for surgical site infections. Air quality should be assessed during microbiological commissioning of new ORs and as required thereafter. Despite many modern methods of sampling air, developing countries mostly depended on conventional methods. This was studied in two ORs of the National Hospital of Sri Lanka (NHSL) with different ventilation system; a conventional ventilation (CV) and a laminar air flow (LAF). Both ORs were sampled simultaneously by two different methods, the settle plate and sampler when empty and during use for a defined time period. Laboratory work was done in the Medical Research Institute. The two methods of sampling showed moderate but highly significant correlation. The OR with CV was significantly more contaminated than LAF when empty as well as during use by both methods. Overall, the difference in contamination was more significant when sampled by the sampler. Differences in contamination in empty and in-use ORs were significant in both ORs, but significance is less in LAF rooms. The consistent and significant correlation between settle plate and sampler showed that the settle plate is an acceptable method. The LAF theatre showed less contamination while empty and during use as expected. Air contamination differences were more significant when sampled with sampler indicating that it is a more sensitive method. Both CV and LAF ORs of the NHSL did not meet the contamination standards for empty theatres but met the standards for in-use indicating that the theatre etiquette was acceptable.

Workspace, dexterity and dimensional optimization of microhexapod

2015 ◽  
Vol 35 (4) ◽  
pp. 341-347 ◽  
Author(s):  
E. Rouhani ◽  
M. J. Nategh
Keyword(s):  
Degrees Of Freedom ◽  
Optimization Problem ◽  
Screw Theory ◽  
Design Parameters ◽  
Dimensional Synthesis ◽  
Content Type ◽  
Workspace Analysis ◽  
The Difference ◽  
Flexure Joints ◽  
6 Degrees Of Freedom

Purpose – The purpose of this paper is to study the workspace and dexterity of a microhexapod which is a 6-degrees of freedom (DOF) parallel compliant manipulator, and also to investigate its dimensional synthesis to maximize the workspace and the global dexterity index at the same time. Microassembly is so essential in the current industry for manufacturing complicated structures. Most of the micromanipulators suffer from their restricted workspace because of using flexure joints compared to the conventional ones. In addition, the controllability of micromanipulators inside the whole workspace is very vital. Thus, it is very important to select the design parameters in a way that not only maximize the workspace but also its global dexterity index. Design/methodology/approach – Microassembly is so essential in the current industry for manufacturing complicated structures. Most of the micromanipulators suffer from their restricted workspace because of using flexure joints compared to the conventional ones. In addition, the controllability of micromanipulators inside the whole workspace is very vital. Thus, it is very important to select the design parameters in a way that not only maximize the workspace but also its global dexterity index. Findings – It has been shown that the proposed procedure for the workspace calculation can considerably speed the required calculations. The optimization results show that a converged-diverged configuration of pods and an increase in the difference between the moving and the stationary platforms’ radii cause the global dexterity index to increase and the workspace to decrease. Originality/value – The proposed algorithm for the workspace analysis is very important, especially when it is an objective function of an optimization problem based on the search method. In addition, using screw theory can simply construct the homogeneous Jacobian matrix. The proposed methodology can be used for any other micromanipulator.

Closed-Form Correlation of Buildings Energy Use With Key Design Parameters Calibrated Using a Genetic Algorithm

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Raed I. Bourisli ◽  
Adnan A. AlAnzi
Keyword(s):  
Genetic Algorithm ◽  
Closed Form ◽  
Energy Use ◽  
Building Design ◽  
Office Buildings ◽  
Design Parameters ◽  
Wide Range ◽  
Variable Function ◽  
Real Coded Genetic Algorithm ◽  
The Difference

This work aims at developing a closed-form correlation between key building design variables and its energy use. The results can be utilized during the initial design stages to assess the different building shapes and designs according to their expected energy use. Prototypical, 20-floor office buildings were used. The relative compactness, footprint area, projection factor, and window-to-wall ratio were changed and the resulting buildings performances were simulated. In total, 729 different office buildings were developed and simulated in order to provide the training cases for optimizing the correlation’s coefficients. Simulations were done using the VisualDOE TM software with a Typical Meteorological Year data file, Kuwait City, Kuwait. A real-coded genetic algorithm (GA) was used to optimize the coefficients of a proposed function that relates the energy use of a building to its four key parameters. The figure of merit was the difference in the ratio of the annual energy use of a building normalized by that of a reference building. The objective was to minimize the difference between the simulated results and the four-variable function trying to predict them. Results show that the real-coded GA was able to come up with a function that estimates the thermal performance of a proposed design with an accuracy of around 96%, based on the number of buildings tested. The goodness of fit, roughly represented by R2, ranged from 0.950 to 0.994. In terms of the effects of the various parameters, the area was found to have the smallest role among the design parameters. It was also found that the accuracy of the function suffers the most when high window-to-wall ratios are combined with low projection factors. In such cases, the energy use develops a potential optimum compactness. The proposed function (and methodology) will be a great tool for designers to inexpensively explore a wide range of alternatives and assess them in terms of their energy use efficiency. It will also be of great use to municipality officials and building codes authors.

Effects of Diarrhea Associated with Specific Enteropathogens on the Growth of Children in Rural Bangladesh

PEDIATRICS ◽  
1984 ◽  
Vol 73 (6) ◽  
pp. 799-805 ◽  
Author(s):  
Robert E. Black ◽  
Kenneth H. Brown ◽  
Stan Becker
Keyword(s):  
Linear Growth ◽  
Protein Energy Malnutrition ◽  
Growth Control ◽  
Reference Population ◽  
Enterotoxigenic Escherichia Coli ◽  
E Coli ◽  
Rural Bangladesh ◽  
Protein Energy ◽  
Negative Effect ◽  
The Difference

Village-based surveillance data from longitudinal studies in rural Bangladesh have been used to evaluate the nutritional consequences of infectious diseases, including diarrhea due to specific pathogens. The prevalences of specific illnesses were related to the ponderal and linear growth of young children for 2-month and 1-year periods. Of the common illnesses, only diarrhea had a significant inverse relationship with increments of weight during 2-month periods and of length during 1 year. Diarrhea accounted for 20% of the difference in linear growth between the study children and the international reference population during the first 5 years of life. Diarrhea associated with enterotoxigenic Escherichia coli had a significant negative effect on the bimonthly weight gain of children in this community and shigellosis had the strongest negative effect on bimonthly and annual linear growth. Control of diarrhea due to enterotoxigenic E coli and Shigella would not only substantially diminish diarrheal morbidity but would also improve the growth of children and thereby reduce the prevalence of protein-energy malnutrition.

FC 068QUALITY OF LIFE OVER TIME IN OLDER MEN AND WOMEN WITH ADVANCED CKD - RESULTS FROM THE EQUAL STUDY

2021 ◽  
Vol 36 (Supplement_1) ◽  
Author(s):  
Nicholas Chesnaye ◽  
Yvette Meuleman ◽  
Esther De Rooij ◽  
Friedo W Dekker ◽  
Marie Evans ◽  
...  
Keyword(s):  
Harmful Effect ◽  
Patient Characteristics ◽  
P Value ◽  
Joint Models ◽  
Cross Sectional ◽  
Linear Interaction ◽  
Men And Women ◽  
Negative Effect ◽  
The Difference ◽  
Over Time

Abstract Background and Aims Differences between the sexes are apparent in the epidemiology of CKD. Cross-sectional studies show that women consistently report a poorer health-related quality of life (QoL) than men, however, longitudinal studies are lacking. Here we investigate the sex-specific evolution of QoL over time in advanced CKD. As a secondary aim, we explore the sex-specific determinants of QoL. Method EQUAL is an observational prospective cohort study in stages 4 and 5 CKD patients ≥65 years not on dialysis with an incident estimated glomerular filtration rate (eGFR) < 20 ml/min/1.73m². Data on QoL (measured using the RAND-36), clinical and demographic patient characteristics were collected between April 2012 and September 2020. QoL trajectories were modelled by sex using linear mixed models, and joint models were applied to deal with informative censoring. We followed patients until death or dialysis initiation. Results We included 5151 QoL measurements in 1416 patients over a total of 1986 person years of follow-up. Overall, the physical component summary (PCS) declined with 2.0 (95% CI 1.4-2.6) points and the mental component summary (MCS) by 2.4 (95% CI 1.8-3.0) points per year. Although women had overall lower QoL scores, figure 1 demonstrates that PCS and MCS declined more than twice as fast in men (PCS: 2.4 per year, 95% CI 1.7 – 3.1, MCS: 2.9 per year, 95% CI 2.2 – 3.6) compared with women (PCS: 1.1 per year, 95% CI -0.2 – 2.0, MCS: 1.5 per year, 95% CI 0.5 – 2.4). We identified a non-linear interaction effect between sex and eGFR levels on QoL, demonstrating a stronger negative effect of decreased eGFR on both PCS (p=0.02) and MCS (p=0.04) in men compared with women. Subsequent adjustment for renal decline attenuated the difference in rate of QoL decline between men and women (difference after adjustment; PCS: 1.1, 95% CI -0.1 – 2.2, MCS: 1.2, 95% 0.0 – 2.3). In univariable analyses, higher serum haemoglobin was more beneficial to QoL in men compared to women (p-value for interaction; PCS: p=0.03, MCS: p=0.01). Higher serum phosphate had a strong harmful effect on both PCS and MCS in men, but not in women (PCS & MCS: p<0.001). The presence of pre-existing diabetes had a negative effect on PCS and MCS in men, but to a lesser extent in women (PCS: p=0.02, MCS: p=0.01). Conclusion Despite the higher overall QoL reported by men, both their physical and mental QoL declined approximately twice as fast compared with women. The faster decline in men was mediated in part by their lower levels of renal function, which had a stronger impact on their QoL as compared with women. Furthermore, in exploratory analyses we identified that high levels of phosphate, low levels of haemoglobin, and pre-existing diabetes were more detrimental to QoL in men than in women.

The impact of credit risk on the financial stability of commercial banks in Vietnam

2021 ◽  
Vol 11 (2) ◽  
pp. 67-80
Author(s):  
Nguyen Quoc Anh ◽  
Duong Nguyen Thanh Phuong
Keyword(s):  
Credit Risk ◽  
Commercial Banks ◽  
Financial Stability ◽  
Dynamic Panel Data ◽  
Z Score ◽  
Return On Equity ◽  
Score Analysis ◽  
Negative Effect ◽  
The Difference ◽  
The Impact

This study investigates the impact of credit risk on the financial stability of Vietnamese commercial banks. The paper uses the Z-score to proxy the financial stability of banks. We use the data of 27 Vietnamese commercial banks on BankScope, during 2010 - 2019. The paper applied a dynamic panel data approach; the selected method is the difference GMM (DGMM). The key question discussed is which factor impacts on Z-score. Analysis results show the negative effect of non-performing loans on the financial stability of banks. When commercial banks have higher non-performing loans, the lower the financial stability is. Additionally, bank-specific variables such as equity on asset ratio, the return on equity, the size of the bank and set of macroeconomic variables affect the bank’s financial stability. Based on the analysis results, we imply relevant policies for the State Bank of Vietnam and commercial banks.

Improving Gerotor Pump Performance Trough Design, Modeling and Simulation

2021 ◽  
Author(s):  
Lozica Ivanović ◽  
Miloš Matejić
Keyword(s):  
Low Noise ◽  
Operating Conditions ◽  
Design Parameters ◽  
Pump Efficiency ◽  
Hydraulic Systems ◽  
Wear Process ◽  
Gerotor Pump ◽  
Gerotor Pumps ◽  
Negative Effect ◽  
Compact Design

Gerotor pumps are well known by a compact design, simple structure and low noise level, which makes them suitable for use in the automotive industry, and especially in hydraulic systems for engine lubrication. One of the main disadvantages of gerotor pumps is the inability to adjust to wear, which significantly reduces the pump efficiency. In order to mitigate the negative effect of the inevitable wear process, this paper presents a methodology for determining the optimal combination of trochoid gears design parameters for a defined aspect. An appropriate mathematical model has been developed to analyze the effect of changes in gear design parameters in relation to maximum contact stresses, pressure changes in gerotor pump chambers and wear rate proportional factor (WRPF). Verification of the developed models was performed by realizing physical pairs of gears and laboratory experiments with simulation of pump operating conditions. The results and conclusions presented in this paper, with an emphasis on the actual work processes, bring very important perspectives for the gerotor pumps design with improved performance.

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