Improved Design Parameters for a Liquid Desiccant Dehumidifier in Confined Spaces

Solar Energy ◽  
2005 ◽  
Author(s):  
D. Dong ◽  
M. Liu
Keyword(s):  
Energy Consumption ◽  
Ventilation System ◽  
Exhaust System ◽  
Design Parameters ◽  
Confined Space ◽  
Confined Spaces ◽  
Exhaust Ventilation ◽  
Moisture Condensation ◽  
Improved Design ◽  
Control Application

Investigations of a desiccant dehumidifier system have been performed for humidity control application in confined spaces. A previous study revealed that the base dehumidifier system can reduce moisture condensation by 22% over a conventional exhaust ventilation system. The current study aims to develop improved design requirements for a desiccant dehumidifier. The energy consumption of an exhaust ventilation system and an improved dehumidifier system was compared. To investigate the improved desiccant dehumidification system, numerical simulations were conducted and an objective function was established. This paper presents simulated results for an existing desiccant dehumidification system and an improved system, in which improved parameters are used. Use of the improved design parameters can reduce moisture condensation by 26.6% over a base dehumidifier system and shorten the dehumidifier performance period by 14%. Energy consumption with the sole use of an exhaust system is compared with that of the improved dehumidifier system under the same conditions. The results show that energy consumption can be substantially reduced, by 63%, in the improved dehumidifier system with the same amount of moisture condensation on surfaces of the confined space.

METHOD OF SELECTION AND CALCULATION DEVICES AIR CLEANING FROM CONDENSED AEROSOLS

2016 ◽  
Vol 6 (2) ◽  
pp. 14-18
Author(s):  
Denis N. VATUZOV ◽  
Svetlana M. PURING
Keyword(s):  
Energy Efficiency ◽  
Ventilation System ◽  
Design Parameters ◽  
Local Exhaust Ventilation ◽  
Improve Energy Efficiency ◽  
Air Cleaning ◽  
Exhaust Ventilation ◽  
Recovery System ◽  
Degree Of Purification ◽  
Ventilation Management

This article defines the options to improve the efficiency of local exhaust ventilation systems by incorporating into the circuit from the air cleaning devices droplet aerosol. Schemes connecting cleaning apparatus in ventilation management system are worked out. In the first embodiment, the placement aerozoleulovitelya purified ventilation air is discharged directly to the atmosphere, in the second embodiment, the cleaned air is used in the recovery system, which is removed after the street. The feasibility of using the heat exchanger in the scheme is justified by comparing the technical and economic options and the need to improve energy efficiency. The method of selection and calculation of air cleaning devices from droplet sprays, on the basis of which it is possible to determine the design parameters of the system, to evaluate the amount of captured material, and choose the most appropriate in each case unit, focusing on the desired performance of the ventilation system, the necessary degree of purification and the area for mounting the device.

scholarly journals Influence of Building Air Tightness on Energy Consumption of Ventilation System in Nearly Zero Energy Residential Buildings

2019 ◽  
Vol 111 ◽  
pp. 03074
Author(s):  
Wei Liu ◽  
Zhen Yu ◽  
Jianlin Wu ◽  
Huai Li ◽  
Caifeng Gao ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Control Strategy ◽  
Energy Recovery ◽  
Residential Buildings ◽  
Ventilation System ◽  
Design Parameters ◽  
System Control ◽  
Recovery Efficiency ◽  
Zero Energy ◽  
Air Tightness

Building air tightness increased quickly in recent years as nearly zero energy buildings concept gradually drawn more attentions from the industry. Ventilation system plays an important role for the indoor air quality control in residential buildings with good air tightness. The energy consumption of the ventilation system is a significant part of the overall energy consumption of low energy residential building. The influence of the building air tightness on the energy consumption of ventilation system was not addressed sufficiently in previous studies. This paper analyses the quantitative relations between building air tightness, energy recovery efficiency and ventilation system control strategy. A mathematical model of the heating and cooling energy consumption in residential buildings is proposed, which takes building air tightness, energy recovery efficiency and control strategy of ventilation system as major input parameters. Equivalent COP of ventilation energy recovery system is proposed as an energy efficiency index of the ventilation system. It can be used as a criterion to decide the optimal design parameters of nearly zero residential buildings in different climate conditions.

scholarly journals Maintenance of Passive House Standard in the Light of Long-Term Study on Energy Use in a Prefabricated Lightweight Passive House in Central Europe

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2801 ◽  
Author(s):  
Krzysztof Wąs ◽  
Jan Radoń ◽  
Agnieszka Sadłowska-Sałęga
Keyword(s):  
Energy Consumption ◽  
Energy Use ◽  
Ventilation System ◽  
Primary Energy ◽  
Operating Conditions ◽  
Design Parameters ◽  
Passive House ◽  
Long Term Study ◽  
House Standard

This article presents the results of experimental research on energy consumption of a prefabricated lightweight passive house located in the south of Poland. The key design parameters of the building were as follows: orientation maximizing heat gains from solar radiation, high thermal insulation of partitions, heat provided by ground source heat pump, and mechanical ventilation system with the heat exchanger. The measurements were performed in normal operating conditions in an inhabited building, throughout the years 2011–2019. For the year 2012, the article also presents the detailed structure of electricity used for particular devices. The objective of the research was to verify whether, in the long term, the building fulfils the energy consumption requirements for passive buildings. The measurements showed that energy consumption for heating was 50% lower than the value required from passive buildings. However, primary energy consumption for the entire building was exceeded already in the second year of research. This was caused by two factors: human behaviors and the type of primary energy source. The research concludes that the maintenance of passive house standard is vulnerable to human impact and difficult in the case of power source characterized by high index of expenditure on non-renewable primary energy. The article also presents recommendations on how to restore the passive house standard in the building.

scholarly journals Effect of Mechanical Ventilation on Accidental Hydrogen Releases—Large-Scale Experiments

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3008
Author(s):  
Agnieszka W. Lach ◽  
André V. Gaathaug
Keyword(s):  
Mechanical Ventilation ◽  
Mass Flow ◽  
Large Scale ◽  
Ventilation System ◽  
Hydrogen Gas ◽  
Forced Ventilation ◽  
British Standard ◽  
Confined Spaces ◽  
Series Of Experiments ◽  
Rate Limit

This paper presents a series of experiments on the effectiveness of existing mechanical ventilation systems during accidental hydrogen releases in confined spaces, such as underground garages. The purpose was to find the mass flow rate limit, hence the TPRD diameter limit, that will not require a change in the ventilation system. The experiments were performed in a 40 ft ISO container in Norway, and hydrogen gas was used in all experiments. The forced ventilation system was installed with a standard 315 mm diameter outlet. The ventilation parameters during the investigation were British Standard with 10 ACH and British Standard with 6 ACH. The hydrogen releases were obtained through 0.5 mm and 1 mm nozzles from different hydrogen reservoir pressures. Both types of mass flow, constant and blowdown, were included in the experimental matrix. The analysis of the hydrogen concentration of the created hydrogen cloud in the container shows the influence of the forced ventilation on hydrogen releases, together with TPRD diameter and reservoir pressure. The generated experimental data will be used to validate a CFD model in the next step.

Life Augmentation of Turbine Exhaust System Compensators Through Integrated MADM Optimization Approach of Stress Based Fatigue Cycles

2021 ◽  
Author(s):  
Nitin D. Pagar ◽  
Amit R. Patil
Keyword(s):  
Exhaust System ◽  
Optimization Methods ◽  
Fractional Factorial ◽  
Design Parameters ◽  
Optimization Approach ◽  
Auxiliary Equipment ◽  
Maximum Expansion ◽  
Optimal Configurations ◽  
Selection Of ◽  
Turbine Exhaust

Abstract Exhaust expansion joints, also known as compensators, are found in a variety of applications such as gas turbine exhaust pipes, generators, marine propulsion systems, OEM engines, power units, and auxiliary equipment. The motion compensators employed must have accomplished the maximum expansion-contraction cycle life while imposing the least amount of stress. Discrepancies in the selecting of bellows expansion joint design parameters are corrected by evaluating stress-based fatigue life, which is challenging owing to the complicated form of convolutions. Meridional and circumferential convolution stress equations that influencing fatigue cycles are evaluated and verified with FEA. Fractional factorial Taguchi L25 matrix is used for finding the optimal configurations. The discrete design parameters for the selection of the suitable configuration of the compensators are analysed with the help of the MADM decision making techniques. The multi-response optimization methods GRA, AHP, and TOPSIS are used to determine the parametric selection on a priority basis. It is seen that weighing distribution among the responses plays an important role in these methods and GRA method integrated with principal components shows best optimal configurations. Multiple regression technique applied to these methods also shows that PCA-GRA gives better alternate solutions for the designer unlike the AHP and TOPSIS method. However, higher ranked Taguchi run obtained in these methods may enhance the suitable selection of different design configurations. Obtained PCA-GRG values by Taguchi, Regression and DOE are well matched and verified for the all alternate solutions. Further, it also shows that stress based fatigue cycles obtained in this analysis for the L25 run indicates the range varying from 1.13 × 104 cycles to 9.08 × 105 cycles, which is within 106 cycles. This work will assist the design engineer for selecting the discrete parameters of stiff compensators utilized in power plant thermal appliances.

scholarly journals Cockroaches traverse crevices, crawl rapidly in confined spaces, and inspire a soft, legged robot

2016 ◽  
Vol 113 (8) ◽  
pp. E950-E957 ◽  
Author(s):  
Kaushik Jayaram ◽  
Robert J. Full
Keyword(s):  
Body Weight ◽  
High Speed ◽  
Stride Length ◽  
Body Height ◽  
Legged Robot ◽  
Confined Space ◽  
Performance Limits ◽  
Biological Inspiration ◽  
Confined Spaces ◽  
Postural Changes

Jointed exoskeletons permit rapid appendage-driven locomotion but retain the soft-bodied, shape-changing ability to explore confined environments. We challenged cockroaches with horizontal crevices smaller than a quarter of their standing body height. Cockroaches rapidly traversed crevices in 300–800 ms by compressing their body 40–60%. High-speed videography revealed crevice negotiation to be a complex, discontinuous maneuver. After traversing horizontal crevices to enter a vertically confined space, cockroaches crawled at velocities approaching 60 cm⋅s−1, despite body compression and postural changes. Running velocity, stride length, and stride period only decreased at the smallest crevice height (4 mm), whereas slipping and the probability of zigzag paths increased. To explain confined-space running performance limits, we altered ceiling and ground friction. Increased ceiling friction decreased velocity by decreasing stride length and increasing slipping. Increased ground friction resulted in velocity and stride length attaining a maximum at intermediate friction levels. These data support a model of an unexplored mode of locomotion—“body-friction legged crawling” with body drag, friction-dominated leg thrust, but no media flow as in air, water, or sand. To define the limits of body compression in confined spaces, we conducted dynamic compressive cycle tests on living animals. Exoskeletal strength allowed cockroaches to withstand forces 300 times body weight when traversing the smallest crevices and up to nearly 900 times body weight without injury. Cockroach exoskeletons provided biological inspiration for the manufacture of an origami-style, soft, legged robot that can locomote rapidly in both open and confined spaces.

The Simulation Experiments Research of Plow Bit Cutting Coal Rock Basing on Ls-Dyna

2011 ◽  
Vol 228-229 ◽  
pp. 1035-1038
Author(s):  
Zhi Yong Hao ◽  
Jun Mao
Keyword(s):  
Energy Consumption ◽  
Coal Seam ◽  
Separation Distance ◽  
Design Parameters ◽  
Cutting Depth ◽  
Element Analysis ◽  
Cutting Resistance ◽  
Cutting Energy ◽  
3D Simulation Model ◽  
Depth Separation

Using finite element analysis software ANSYS/ LS-DYNA, establishing the plow cutting coal seam 3D simulation model, simulating plow bit cutting coal seam dynamic process. under study, obtaining plow bit the cutting resistance, plow speed of time process curve, analyzing the influence on cutting energy consumption of the different cutting depth, separation distance and width, reaching the rule of cutting energy consumption changing with plow bits’ structure parameter and design parameters, in order to reduce the energy consumption and resistance, cutting depth and plow bits spacing ought to be selected by the real coal seam face conditions.

scholarly journals Droplet and Aerosol Suspension Times in Ambient Air in Confined Spaces and Transmission of COVID-19: Influence of Environmental Factors

2021 ◽  
Vol 13 (2) ◽  
pp. 495-506
Author(s):  
M. R. Islam ◽  
S. H. Naqib
Keyword(s):  
Relative Humidity ◽  
Environmental Factors ◽  
Ambient Air ◽  
Confined Space ◽  
Natural Processes ◽  
Confined Spaces ◽  
Potential Source ◽  
Aerosol Droplet ◽  
Exhaled Air ◽  
Mode Of Transmission

The COVID‑19 pandemic, alternatively known as the coronavirus pandemic, is an unfolding pandemic of coronavirus disease 2019 (COVID‑19) across the entire globe in an unprecedented proportion. COVID-19 is caused by severe acute respiratory syndrome coronavirus 2. The mode of transmission of COVID-19 is a subject of intense research. The airborne transmission is one prime possibility. Breathing and talking are natural processes which generate exhaled particles. The exhaled air is an aerosol/droplet composed of naturally produced particulates of varying size. The duration over which the aerosols/droplets are suspended in the air is an important factor. Long suspended aerosols/droplets are potential source of transmission, particularly in confined spaces. We have calculated times of suspension by considering various environmental factors, namely, the ambient temperature and relative humidity in a confined space, in this work. Both temperature and relative humidity affect the suspension time of the exhaled aerosols/droplets with varying degree. The effects of environmental factors are significant for aerosols, particularly for those with small radii. We have discussed the possible implications of our findings in this paper.

scholarly journals Humidity-Sensitive Demand-Controlled Ventilation Applied to Multi-Unit Residential Building – Performance and Energy Consumption in Dfb Continental Climate

2020 ◽  
Author(s):  
Jerzy Sowa ◽  
Maciej Mijakowski
Keyword(s):  
Energy Consumption ◽  
Energy Use ◽  
Energy Savings ◽  
Residential Buildings ◽  
Ventilation System ◽  
Residential Building ◽  
Primary Energy ◽  
Controlled Ventilation ◽  
Demand Controlled Ventilation ◽  
Continental Climate

A humidity-sensitive demand-controlled ventilation system is known for many years. It has been developed and commonly applied in regions with an oceanic climate. Some attempts were made to introduce this solution in Poland in a much severe continental climate. The article evaluates this system's performance and energy consumption applied in an 8-floor multi-unit residential building, virtual reference building described by the National Energy Conservation Agency NAPE, Poland. The simulations using the computer program CONTAM were performed for the whole hating season for Warsaw's climate. Besides passive stack ventilation that worked as a reference, two versions of humidity-sensitive demand-controlled ventilation were checked. The difference between them lies in applying the additional roof fans that convert the system to hybrid. The study confirmed that the application of demand-controlled ventilation in multi-unit residential buildings in a continental climate with warm summer (Dfb) leads to significant energy savings. However, the efforts to ensure acceptable indoor air quality require hybrid ventilation, which reduces the energy benefits. It is especially visible when primary energy use is analyzed.

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