Simulation and Analysis on Desulfurization of Biogas using Iron Oxide Particles

( Cheng-chang Lien ),( Min-wei Wang ),( Ming-hong Ke ),( Tong-bao Zhang ) 한국농업기계학회 2018 한국농업기계학회 학술발표논문집 Vol.23 No.1

Biogas has a great potential for renewable energy, it contained with hydrogen sulfide which can cause metal equipment corrosion. Therefore the Hydrogen sulfide must be remove before uses biogas, in order to remove hydrogen sulfide in biogas that let biogas passed through the desulfurization column during field application. Inside of the desulfurization column has the certain height of iron oxide particles, Hydrogen sulfide in biogas will generates adsorption reaction on the surface of the iron oxide particles and forms iron sulfide to achieve the purpose of biogas purification. The purpose of this study uses computational fluid dynamics (CFD) numerical simulation to simulate the desulfurization column at a certain amount of biogas to obtain the pressure between the inlet and the outlet of the desulfurization column, and also obtained the airflow velocity profile inside the desulfurization column. The results of this simulation are compared with the actual measured pressure data, it shows that both have a good consistency. For further, improve the upper end of the exit of the desulfurization column to an inverted funnel shape for comparative analysis, it found that the flow in the inverted funnel at the top of the desulfurization column has obviously slowed down which means the sudden contraction (sudden unremitting). This result will provide help to improve a uniformity of the air velocity in the non-central region of the desulfurization column, in order to promote the iron oxide particles of its effective utilization of biogas desulfurization.

Simulation Analysis of Reducing Wind Effect for Windbreak Fence in front of Simple Greenhouse

( Cheng-chang Lien ),( Wei-ling-sun ),( Jeng-liang Lin ) 한국농업기계학회 2018 한국농업기계학회 학술발표논문집 Vol.23 No.1

Wind damage refers to the direct and indirect damages by strong wind speed to agricultural production. Due to the geographical location of Taiwan, strong winds often destroy simple greenhouse and caused enormous losses of agricultural production. In order to reduce the wind velocity, a windbreak fence installed in front of the simple greenhouse to reduce the wind velocity. The protection zone is defined as the area where the wind velocity is reduced at least 60%. The purpose of this study is simulated the stream flow field for the fence in front of simple greenhouse on wind tunnel experiment using computational fluid dynamics (CFD), the fence is arranged in front of simple greenhouse, and using different wind velocity. The fence with different porosity and tilt angle would be measured each of the flow field distribution and wind velocity behind the fence and also discuss the size protection zone. The result of this simulation shows that the difference porosity of the fence will affect the size of the protected zone. The protection zone will extend 6 to 10 times height of the fence (h). As the porosity of the fence increases, the airflow becomes less complex and the vortex in the protected zone disappears gradually. The height of the protected zone decreases with the increase of the horizontal distance, and it also decreases by the increase of the porosity of the fence. The height of the protected zone decreases slightly by the increase of the tilt angle of the fence. In addition, it is found that the fence with a tilt angle of 0 and a porosity 40% has larger protection zone, while a fence with a tilt angle of 0 and a porosity 0% is prone to cause facilities damage because of the large return flow.

Study on Simulation Analysis of Reduce Speed Effect for Wind Nets in Front of Crop

( Cheng-chang Lien ),( Zhu-yun Yeh ),( Wei-ling Sun ),( Jeng-liang Lin ) 한국농업기계학회 2018 한국농업기계학회 학술발표논문집 Vol.23 No.1

Due to frequent strong winds from its geographical location in Taiwan, which caused serious damage to vegetables and fruit trees, leading to a large loss of agricultural production. Wind nets can be used to reduce the wind speed in front of fruits and vegetables in order to reduce the impact of wind speed. The purpose of this study is to use Computational Fluid Dynamics(CFD), CFD simulation Software was used to simulate wind tunnel experiments with wind nets before fruits and vegetables to understand the wind tunnel with different ventilation rates under certain wind speed 40 m/s, to simulate the change of wind speed and the distribution of flow field behind the wind nets, Analyze and analyze the change of wind field and the effect of reducing the wind. The size of the wind net was 12m^*6m. According to the CFD simulation results, when the strong wind blows through the wind nets, a negative pressure zone will be generated at a horizontal distance of 0h to 10h in the windshield leeway, and the height of the negative pressure zone will gradually decrease as the horizontal distance increases. The height of the negative pressure zone also decreases with the increase of the ventilation rate of the windbreak. In addition, the analysis results show that the ventilation rate of 40% of the windbreak, the negative pressure vortex gradually disappear, and have the best effect of reducing the wind.

Study on Adsorption Desulfurization of Biogas Using Iron Oxide Particles

( Cheng-chang Lien ),( Min-wei Wang ),( Liang-yu Jian ),( Jeng-liang Lin ) 한국농업기계학회 2018 한국농업기계학회 학술발표논문집 Vol.23 No.1

The contained hydrogen sulfide in biogas leads to corrosion of metal equipment. In addition, the high concentration of hydrogen sulfide can also hurt the health of humans and animals. As to be a renewable energy with both environmental protection and safety, biogas must be removed and purified before being used. In this study, a solid-state desulfurization device was designed. The biogas flow through the bottom of the transparent desulfurization column which is made of acrylic glass, the iron oxide particles were placed in the desulfurization column as desulfurizer, change the biogas flow and the height of iron oxide particles in the desulfurization column to experiment on desulfurization, measure the concentration of hydrogen sulfide adsorbed by the iron oxide particles at the above of the desulfurization column, then discuss the change of the hydrogen sulfide removed rate in biogas with the experimental period. The experimental result shows that the removed rate of hydrogen sulfide decreases with the increase of biogas flow, and it also increases with the iron oxide particle height in the desulfurization column, the longer stagnation inside the desulphurization column, will cause the better removed efficiency of hydrogen sulfide. In addition, the removed efficiency of hydrogen sulfide gradually decreases with the increase of the desulfurization period. The average desulfurization efficiency was 95.16% at biogas flow of 25 ℓ / min, iron oxide particle height of 15.3 cm and desulfurization period is 70 minutes.

Linking an Anxiety-Related Personality Trait to Cardiac Autonomic Regulation in Well-Defined Healthy Adults: Harm Avoidance and Resting Heart Rate Variability

Lien-Cheng Kao,Yu-Wen Liu,Nian-Sheng Tzeng,Terry B. J. Kuo,San-Yuan Huang,Chuan-Chia Chang,Hsin-An Chang 대한신경정신의학회 2016 PSYCHIATRY INVESTIGATION Vol.13 No.4

ObjectiveaaAnxiety trait, anxiety and depression states have all been reported to increase risks for cardiovascular disease (CVD), possibly through altering cardiac autonomic regulation. Our aim was to investigate whether the relationship between harm avoidance (HA, an anxiety-related personality trait) and cardiac autonomic regulation is independent of anxiety and depression states in healthy adults. MethodsaaWe recruited 535 physically and mentally healthy volunteers. Participants completed the Beck Anxiety Inventory (BAI), Beck Depression Inventory (BDI) and Tri-dimensional Personality Questionnaire. Participants were divided into high or low HA groups as discriminated by the quartile value. Cardiac autonomic function was evaluated by measuring heart rate variability (HRV). We obtained the time and frequency-domain indices of HRV including variance (total HRV), the low-frequency power (LF; 0.05–0.15 Hz), which may reflect baroreflex function, the high-frequency power (HF; 0.15–0.40 Hz), which reflects cardiac parasympathetic activity, as well as the LF/HF ratio. ResultsaaThe BDI and HA scores showed associations with HRV parameters. After adjustment for the BDI scores and other control variables, HA is still associated with reduced variance, LF and HF power. Compared with the participants with low HA, those with high HA displayed significant reductions in variance, LF and HF power and a significant increase in their LF/HF ratio. ConclusionaaThis study highlights the independent role of HA in contributing to decreased autonomic cardiac regulation in healthy adults and provides a potential underlying mechanism for anxiety trait to confer increased risk for CVD.

Validation of Pharyngeal Acid Reflux Episodes Using Hypopharyngeal Multichannel Intraluminal Impedance-pH

Yen-Yang Chen,Chen-Chi Wang,Ying-Cheng Lin,John Y Kao,Chun-Yi Chuang,Yung-An Tsou,Ja-Chih Fu,Sheng-Shun Yang,Chi-Sen Chang,Han-Chung Lien 대한소화기 기능성질환∙운동학회 2023 Journal of Neurogastroenterology and Motility (JNM Vol.29 No.1

Background/AimsHypopharyngeal multichannel intraluminal impedance-pH (HMII-pH) technology incorporating 2 trans-upper esophageal sphincter impedance channels has been developed to detect pharyngeal reflux. We used the HMII-pH technique to validate the candidate pharyngeal acid reflux (PAR) episodes based on the dual-pH tracings and determined the interobserver reproducibility. MethodsWe conducted a cross-sectional study in tertiary centers in Taiwan. Ninety patients with suspected laryngopharyngeal reflux and 28 healthy volunteers underwent HMII-pH test when off acid suppressants. Candidate PAR episodes were characterized by pharyngeal pH drops of at least 2 units and reaching a nadir pH of 5 within 30 seconds during esophageal acidification. Two experts manually independently identified candidate PAR episodes based on the dual-pH tracings. By reviewing the HMII-pH tracings, HMII-pH-proven PAR episodes were subsequently confirmed. The consensus reviews of HMII-pH-proven PAR episodes were considered to be the reference standard diagnosis. The interobserver reproducibility was assessed. ResultsA total of 105 candidate PAR episodes were identified. Among them 84 (80.0%; 95% CI, 71.0-87.0%) were HMII-pH-proven PAR episodes (82 in 16 patients and 2 in 1 healthy subject). Patients tended to have more HMII-pH-proven PAR episodes than healthy controls (median and percentile values [25th, 75th, and 95th percentiles]: 0 [0, 0, 3] vs 0 [0, 0, 0], P = 0.067). The concordance rate in diagnosing HMII-pH-proven PAR episodes between 2 independent observers was 92.2%. ConclusionOur preliminary data showed that 80.0% (71.0-87.0%) of the proposed candidate PAR episodes were HMII-pH-proven PAR episodes, among which the interobserver reproducibility was good.

Distal Mean Nocturnal Baseline Impedance Predicts Pathological Reflux of Isolated Laryngopharyngeal Reflux Symptoms

Hua-Nong Luo,Chen-Chi Wang,Ying-Cheng Lin,Chun-Yi Chuang,Yung-An Tsou,Ja-Chih Fu,Sheng-Shun Yang,Chi-Sen Chang,Han-Chung Lien 대한소화기 기능성질환∙운동학회 2023 Journal of Neurogastroenterology and Motility (JNM Vol.29 No.2

Background/AimsDiagnosis of isolated laryngopharyngeal reflux symptoms (ILPRS), ie, without concomitant typical reflux symptoms (CTRS), remains difficult. Mean nocturnal baseline impedance (MNBI) reflects impaired mucosal integrity. We determined whether esophageal MNBI could predict pathological esophagopharyngeal reflux (pH+) in patients with ILPRS. MethodsIn this cross-sectional study conducted in Taiwan, non-erosive or low-grade esophagitis patients with predominant laryngopharyngeal reflux symptoms underwent combined hypopharyngeal multichannel intraluminal impedance-pH monitoring when off acid suppressants. Participants were divided into the ILPRS (n = 94) and CTRS (n = 63) groups. Asymptomatic subjects without esophagitis (n = 25) served as healthy controls. The MNBI values at 3 cm and 5 cm above the lower esophageal sphincter (LES) and the proximal esophagus were measured. ResultsDistal but not proximal esophageal median MNBI values were significantly lower in patients with pH+ than in those with pH– (ILPRS in pH+ vs pH–: 1607 Ω vs 2709 Ω and 1885 Ω vs 2563 Ω at 3 cm and 5 cm above LES, respectively; CTRS in pH+ vs pH–: 1476 vs 2307 Ω and 1500 vs 2301 Ω at 3 cm and 5 cm above LES, respectively, P < 0.05 for all). No significant differences of any MNBI exist between any pH– subgroups and healthy controls. The areas under the receiver operating characteristic curve in the ILPRS group were 0.75 and 0.80, compared to the pH– subgroup and healthy controls (P < 0.001 for both), respectively. Interobserver reproducibility was good (Spearman correlation 0.93, P < 0.0001). ConclusionDistal esophageal MNBI predicts pathological reflux in patients with ILPRS.