Journal Articles - Engineering - 2019
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PublicationPhân tích lý thuyết việc thay thế môi chất R134a trong dãi nhiệt độ trung bình bằng môi chất R450a để bảo vệ môi trường( 2019)Bài báo phân tích lý thuyết khả năng thay thế môi chất R134a (có chỉ số làm nóng địa cầu GWP là 1300) đang được sử dụng rộng rãi trong các tủ lạnh gia đình bằng các môi chất R450a (GWP=547). Việc phân tích nhằm so sánh tính chất nhiệt động, nhiệt độ cuối tầm nén, năng suất lạnh riêng thể tích, năng suất lạnh, công nén và hệ số lạnh khi thay thế cho một hệ thống lạnh đang sử dụng R134a với các điều kiện: nhiệt độ ngưng tụ 50oC, các dãi nhiệt độ bay hơi khác nhau -20, -15, -10, -5 và 0oC, độ quá lạnh 5K, độ quá nhiệt 10K với máy nén Copeland, mã hiệu CS18K6E-PFJ. Kết quả phân tích cho thấy rằng hệ số COP của R450a giảm không đáng kể, chỉ từ 0,15~0,82%, nhiệt độ cuối tầm nén giảm 6~8%, công suất thải nhiệt dàn ngưng giảm từ 13~14%. Ngoài ra, ta không cần phải thay thế các thiết bị trao đổi nhiệt, đường ống dẫn.
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PublicationNghiên cứu tạo giấm tre và than tre từ cây tầm vông phục vụ sản xuất nông nghiệp hữu cơ( 2019)Giấm tre và than tre được biết đến với nhiều ứng dụng trong chăm sóc sức khỏe, chế biến thực phẩm, xử lý môi trường, nông nghiệp và nhiều ứng dụng tiềm năng trong thực tế. Mục tiêu của nghiên cứu đó là tạo ra sản phẩm giấm tre và than tre từ việc ngưng tụ khói của quá trình đốt tầm vông (phần gốc và ngọn loại ra trong quá trình sử dụng) trong thùng phuy ở điều kiện rất ít oxy. Sản phẩm này sau đó được sử dụng cho sản xuất nông nghiệp hữu cơ. Kết quả nghiên cứu cho thấy, cứ 100 kg tầm vông sau khi được cacbon hóa trong lò sẽ cho ra 2,6 lít giấm tre và 24,9 kg than tre.
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PublicationThe dynamics of textile firm responses to the restriction of endocrine disrupting surfactants: a Vietnam case study( 2019)Since textile industry has been claimed to endanger the environment and human health, the insight of textile firm behavior regarding chemical use and discharge is vital for designing environmental risk management strategies. This study aimed to explore the dynamics of responses to the restriction of nonylphenol (NP) and its ethoxylates (NPEOs) among the Vietnamese textile manufacturers from the perspectives of attitude and the perceptions of adaptabilities, risks, benefits, and barriers. The chemicals are used as surfactants and are known to be responsible for endocrine disrupting effects. In-depth interviews were conducted with technical specialists from four textile firms and one chemical supplier. Regulatory and market situations with regards to the chemicals were also assessed. The findings revealed varied responses to chemical elimination where perceived technical risk, financial risk, benefits, and barriers played different roles in driving a certain action. The attitude towards chemical restriction was shaped by the trade-off between perceptions of financial risk and benefits and was moderated by market strategy. Efforts, such as enhanced washing or reductions in the dose of NP/NPEOs, imply the potency of continuous discharge of these chemicals into the environment, suggesting critical investigations on NP/NPEOs removal to prioritize actions for balancing between economic growth and environmental protection. Poor access to new policies and technological and chemical innovations was the most important barrier among private firms, highlighting the roles of non-governmental textile and garment industrial/trade associations in enhancing their members’ informative capacity. The study reflects the significance of incorporation of firm behavior research into environmental risk management practice.
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PublicationRemoval of ammonia nitrogen in wastewater by indirect mechanism using electrochemical with Platinum electrode as anode Nature Environment and Pollution Technology( 2018)In this study, platinum (Pt) electrode was used as an anode to remove ammonia in the wastewater by electrolysis. The batch experiments were carried out with various ammonia concentrations in the synthetic wastewater at ambient temperature with and without chloride ions. The results indicated that the optimal condition was pH = 7.0 and current density of 10 mA/cm2. The added NaCl concentration had a significant effect on both, the ammonia removal rate and energy consumption. The ammonia removal performance was 99% with initial ammonia concentration of 25 mg/L after 70 min electrolysis at i=20 mA/cm2; pH 7.0 and 0.03% NaCl. The response functions described the correlation of four variables with NH3 concentration, and NH3 removal efficiency was determined by the response surface methodology (RMS), ANOVA tool with R2 NH3-N = 0.945 and R2 Eff = 0.871
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PublicationA new combination treatment system of ozonation and electrocoagulation for C.I Acid Red 114 dye removal from dyeing wastewater( 2018)In this study, a combined system integrating an ozonation reactor and electrocoagulation (EC) reactor was investigated to remove C.I Acid Red 114 (AR 114) dye in the synthetic dyeing wastewater. The separated EC and ozonation systems were performed as control experiments as well. Hydraulic retention time (HRT) of each system was determined. These systems were operated with 100 mg/L AR 114 dye wastewater at determined optimal conditions. The results showed that colour, dye and CODcr were highly removed by the combined system with only the HRT of 2 min in the ozonation reactor and 0.85 min in the EC reactor. Their average efficiencies were archived up to 93%, 94.25% and 80.6%, respectively. In addition, the energy consumption, volume and mass of waste sludge were evaluated to be low (0.4 kWh/m3, 30 L/m3 and 77 g/m3). When compared between the combined system and the control systems based on the same decolorization performance, the results indicated that the combined system has shorter HRT, less energy consumption than others and less waste sludge generation than the separated EC system.