16 research outputs found

    Carbon footprint of Nepalese healthcare system: A study of Dhulikhel Hospital [version 1; peer review: 2 approved, 1 approved with reservations, 1 not approved]

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    Background: Though direct greenhouse gas emissions cannot be observed in health care sectors, there can exist indirect emissions contributing to global climate change. This study addresses the concept of the carbon footprint and its significance in understanding the environmental impact of human activities, with a specific emphasis on the healthcare sector through gate-to-gate (GtoG) life cycle assessment. Transportation, energy consumption, and solid waste generated by hospitals are the primary sources of carbon emissions. Methods: Different standards, guidelines and parameters were used to estimate emissions from both the primary and secondary data. All steps and sub-steps involved in GtoG were accessed and analyzed within the standard ISO 14040:44 guideline. An extensive review of existing literature was carried out for the evaluation and verification of secondary data. Results: The total carbon footprint of generators, electricity consumption, transportation activities, LPG cylinders, PV systems was found to be 58,780 kg-CO2-eq/yr, 519,794 kg-CO2-eq/yr, 272,375 kg-CO2-eq/yr, 44,494 kg-CO2-eq/yr, 35,283 kg-CO2-eq/yr respectively and the emissions from non-biodegradable solid waste was found to be 489,835 kg-CO2/yr. Local air pollutants such as PM10, CO, SO2, NOX, and VOCs generated by generators and transportation were also estimated. The CH4 emissions from liquid waste were 1177.344 kg CH4/BOD yr, and those from biodegradables were 3821.6954 kg CH4/yr. Conclusions: Healthcare professionals and policymakers can take action to reduce the sector's carbon footprint by implementing best practices and encouraging sustainable behavior. This study can be taken as foundation for further exploration of indirect emissions from healthcare sectors not only in Nepal but also in south Asian scenario

    Sustainability Issues of Biomass based Rural Electrification

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    Airtightness of Nepalese Residential Buildings

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    Experimental field measurements regarding airtightness following the fan pressurisation method were done on 25 typical residential buildings at different locations in Nepal. The field measurement data were classified according to building type and building age.The mean air permeability (Q50 ) for the studied buildings was 6.9 l/s·m2 and the mean air change rate was 55.5 air changes per hour at 50 Pa. The maximum air leakage rate (Q50 ) was 28.4 l/s·m2 for brick masonry in mud mortar type and the minimum recorded was 1.7 l/s·m2 for brick masonry in cement mortar type building. Brick masonry in mud mortar-type buildings was found to be leakier regardless of the building age, and brick masonry in cement mortar-type buildings was comparatively more airtight. Leakage locations identified through visual inspection included the spacing between the door frame and operable door area, horizontal window slider, joint areas of window frame and wall, wood plank-based wall structure, roof joint areas and holes in the wall. This research is the first of its kind in Nepal to assess the airtightness of buildings, and the outcome of this research is one of the key parameters to evaluate the thermal performance of Nepalese buildings scientifically

    Investigation of thermodynamics performance of a heat exchanger-incorporated solar dryer equipped with double-pass flat, v-corrugated, and low-e coated collectors for drying applications

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    In this study, a solar dryer incorporating a flat plate heat exchanger to recover heat from exhaust air was investigated to explore the usability of different types of collectors in the system. Their usability was further evaluated through economic and environmental analyses. Moreover, the thermodynamic performance of the solar dryers was evaluated under two weather conditions in Nepal. Apple drying experiments were conducted for 8 h from 09:00 to 17:00 from February to April 2023 on solar dryers and with open sun drying (OSD) in Dhulikhel, Nepal. The results showed that the low emissivity (low-e) coated aluminum collector was more efficient in terms of collector efficiency and drying rate than collectors with flat or v-corrugated GI absorbers. The average collector efficiency and drying rate were found to be 89 % and 107 g/(h × m2) using the low-e coated aluminum collectors, while the values were 50 % and 84 g/(h × m2) for the GI sheet collector. The results indicated a slight improvement in the performance of v-corrugated collectors, with values of 53 % and 89 g/(h × m2). The drying rate for OSD was found to be 78 g/(h × m2), which was lower than for the dryers with all collectors used in this study. In terms of economic analysis, the dryer equipped with the low-e coated collector was found to be superior, with a payback time of 1.61 years compared to the dryers with flat or v-corrugated GI collectors. Reducing the thermal losses due to radiation by using the low-e coated absorber was shown to be more important than increasing the absorber area using v-corrugated GI sheets

    Effect of graphene nanoplatelets induced ethylene glycol/water mixture (50:50) fluid on lithium-battery cooling

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    Battery technology is the main driving force behind the shift towards emission-free transportation. However, a major obstacle to the widespread adoption of this technology is the need to maintain the battery's temperature at a standard of 27 °C. Traditionally, a mixture of ethylene glycol and water is circulated through the battery pack for cooling, but this method is not sufficient. By contrast, the use of graphene nanoplatelets (GNPs) can improve heat transfer, reducing temperature rise in the battery cell. In this study, a customized battery pack has been simulated using coolants containing varying concentrations of GNPs (ranging from 0.001 vol% to 0.01 vol%) to assess their effectiveness in lowering the operating temperature. The Lagrangian approach has been employed to track the discrete phase particles which couples with Eulerian continuous phase fluid. Results have shown that the pure EG/Water coolant decreases the peak temperature of the system by 16.67% (60 °C–50 °C) which further decreases to 26.85 °C (reduction of 55.25%) till the addition of optimum 0.03 vol% GNP. With the addition of only 0.001 vol% of GNPs, the difference in the peak temperature in the model increases from 10 °C to 31.15 °C as compared to the pure mixture. Higher thermal conductivity, greater surface area and higher specific heat capacity of the particles are attributed for this enhanced cooling

    Exploring aluminum as a solid thermal storage medium for solar cooking application: An experimental investigation coupled with numerical modeling using OpenFOAM

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    The intermittent nature of solar energy presents a significant challenge to its reliability, particularly in applications that require a consistent energy supply, such as cooking. This issue is especially critical in emerging economies with abundant solar resources, where sustainable energy solutions are needed to reduce reliance on traditional fuels. To address this challenge, this study introduces a novel solar thermal storage (STS), utilizing a metal-based material to accumulate and retain heat for off-sunshine hour cooking. The research focuses on optimizing aluminium as the STS material, evaluating its temperature suitability, efficiency, and heat retention capabilities for household solar cooking applications. Numerical simulations using the OpenFOAM framework were conducted to analyze heat transfer within the cooker, determining the optimal size of the aluminium block based on existing literature and predefined parameters. Practical experiments, including solar-induced heating-cooling cycles and controlled cooking tests, were carried out to validate the findings. Experimental results demonstrate STS's ability to efficiently absorb and retain heat, reaching a maximum of 235 °C during a 5.5-h heating session. The water boiling experiment further confirmed STS's practical utility, effectively transferring stored heat to cooking tasks and sustaining temperatures up to 160 °C even after the test. Additionally, experiments with black lentils and chicken stew highlighted aluminium's suitability for practical cooking applications, showcasing its ability to sustain high temperatures and efficiently transfer stored heat despite longer cooking times. The study's novelty lies in integrating numerical modeling with experimental analysis to optimize STS systems, providing practical guidelines for efficient thermal storage in cooking applications. This research advances beyond previous efforts by providing a validated methodology for the design and optimization of thermal storage systems. It improves the reliability and adaptability of solar energy for cooking applications

    Seasonal influence on urban dust PAH profile and toxicity in Sydney, Australia

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    Road dust is one of the major threats to the urban environment due to wash-off of dust to the surrounding catchments during wet weather period. The dust contains wide range of toxic contaminants such as heavy metals, polycyclic aromatic hydrocarbons (PAHs) and endocrine disrupting chemicals. Among the toxic contaminants, PAHs are of environmental concern due to their potential carcinogenic and mutagenic effect besides endocrine disruptive behaviour. Eighteen road dust samples from Sydney were collected in different time periods for a year and analysed for 16 US EPA PAHs. Total PAHs content range in the dust was 9-105 μg/g. Total and individual PAH contents were highest in the finest size fraction

    Life cycle energy use and carbon emission of a modern single-family residential building in Nepal

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    The rapid urbanization and rural-urban migration trends have led to an increase in building construction activities, shifting from traditional practices to modern concrete structures. However, this transition has imposed significant environmental pressures, including heightened resource and energy demands, resulting in increased emissions. To gauge the environmental impact of construction, a thorough examination of each phase is crucial. This study used the Life Cycle Assessment (LCA) tool, based on ISO 14040:2006, ISO 14044:2006, and EN 15978:2011, to evaluate the carbon dioxide equivalent (CO2-eq) emissions throughout the complete life cycle of a modern single-family residential building. The findings reveal a total energy use of 6411.33 MJ per square meter and emissions of 718.35 kg CO2-eq per square meter over the building's lifespan of 50 years. Notably, the production of building materials and the construction phase contribute to the highest percentage (60.29%) of the total life cycle emissions owing to 49.51% of energy use. In contrast, emissions during the operational phase are relatively lower, attributed to increased electricity usage for cooking and minimal energy consumption for heating and cooling. Additionally, the study suggests that achieving complete electricity sufficiency within the country could reduce building emissions by 39.30%, as fossil fuel-based imports from India would be replaced with cleaner hydroelectricity
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