Exergy, Performance And Environmental Impact Analysis Of Compression Refrigeration Systems

Major concern in refrigeration hinges largely on energy conservation, environmental safety and efficient cooling system. The concept of quality of useful energy which invariably leads to energy conservation is naturally related to exergy. This study therefore experimentally conducts exergy, performance and environmental impact analysis of compression refrigeration systems using R134a, R410a and R407c, refrigerants. The experiment was performed using a modified exiting R134a refrigerating system. The refrigerator was built with Scroll compressor, 48m3 evaporator space, 1m throttle length and 0.2mm array of rods in the condensing unit coupled with thermocouple K attached at the various components and a digital 10^-3 accuracy weighing scale for charging refrigerant in the required grams. The results show that for 100 grams charge of the refrigerants, the exergetic efficiency, coefficient of performance (COP) and the degree of environmentally friendliness of each of the refrigerants are of order R410a > R407c,> R134a and for 80 grams charge of the refrigerants, the order of performance is R410a > R134a> R407c. While for 60 grams charge of the refrigerants, the exergetic efficiency, coefficient of performance and the degree of environmentally friendliness of each of the refrigerants are of order R407c> R410a > R134a, that of 40 grams charge of the refrigerants is of order R134a> R407c> R410a. The study therefore established that irrespective of the grams charge values of the investigated refrigerants used, R410a is the best, closely followed by R134a and lastly R407c

Experimental performance of LPG refrigerant charges with varied concentration of TiO2 nano-lubricants in a domestic refrigerator

This article present an experimental investigation of varied mass charges of Liquefied Petroleum Gas (40 g, 50 g, 60 g and 70 g) enhanced with varied TiO2 nanoparticle/mineral oil concentrations (0.2 g/L, 0.4 g/L and 0.6 g/L nanolubricants) in a R134a compressor of a domestic refrigerator. Performance tests investigated at steady state included: pull down time, power consumption, compressor power input, cooling capacity and coefficient of performance (COP). Analysis was based on temperature and pressure readings obtained from appropriate gauges attached to the test rig. Refrigerant property characteristics were obtained using Ref-Prop NIST 9.0 software. Results obtained showed almost equal evaporator air temperatures and reduction in power consumption for all tested nano-lubricant concentrations except at 70 g charge of LPG using 0.6 g/L nano-lubricant. Furthermore, the lowest compressor power input was found to be 21 W and obtained using 70 g of LPG with either of 0.2 g/L or 0.4 g/L nano-lubricants. At 70 g of LPG using 0.6 g/L concentration of nano-lubricant, highest cooling capacity index of 65 W was obtained while the highest COP of 2.8 was obtained with 40 g charge of LPG using 0.4 g/L concentration of nanolubricant. In conclusion, LPG-TiO2 nano-lubricant mixture works safely and efficiently in domestic refrigerators without modification of capillary tube length, but requires adequate optimization

Biodiesel production from palm olein: A sustainable bioresource for Nigeria

Dangerous environmental consequences and market unpredictability of fossil fuels have necessitated the need for sustainable large-scale production of biofuel in Nigeria. Unrefined palm oil (UPO) is a significant product of commercially available oil palm plants in the country. This study experimentally investigates the production of biodiesel from refined, bleached and deodorised (RBD) palm olein extracted from UPO obtained from batch reactors. The transesterification process of the RBD palm olein with methanol and in the presence of potassium hydroxide (KOH) catalyst produced biodiesel with a 62.5% yield, thus confirming its feasibility for mass production. The derived biodiesel has properties equivalent to ASTM D792 standard for biodiesel fuels

The perceptions of social responsibility for community resilience to flooding: the impact of past experience, age, gender and ethnicity

Community resilience to flooding depends, to a large extent, on the participation of community members to take more responsibility for enhancing their own resilience. The perception of social responsibility (SR) which is argued to be one of the antecedents influencing individual’s willingness to undertake resilient behaviours can significantly contribute to community resilience through individual and collective actions. Understanding of factors influencing the perceptions of SR of individuals within community might help with developing strategies to increase the perceptions of SR. This research explores perceptions of SR in relation to flooding for householders and local businesses and establishes their relationships with experience of flooding and demographic factors of age, gender and ethnicity. The data were obtained via a questionnaire survey of three communities in Birmingham and one community in South East London, UK, three with experience of flooding and one without. A total of 414 responses were received and used in the multiple regression analysis. The analysis identified ‘experience of flooding’, ‘age’ and ‘South Asian’ ethnic group as significant variables, suggesting that older individuals from South Asian ethnic groups with previous experience of flooding are likely to be more socially responsible than others without these attributes

Prevalence of malnutrition and vitamin A deficiency in Nigerian preschool children subsisting on high intakes of carotenes

The prevalence of malnutrition and vitamin A deficiency was determined in 204 preschool children of both sexes aged 3–57 months. The children were recruited from 2 rural communities of Atakumosa Local Government Area of Osun State in South West Nigeria. Dietary vitamin A intake was estimated from frequency of consumption of locally available vitamin A containing food items. Vitamin A status of the children was assessed from concentration of retinol in plasma. Nutritional status was assessed from height and weight compared with international reference standards. The results indicate widespread malnutrition among the children. The prevalence of stunting (low height for age) was 60.8% while prevalence of wasting (low weight for height) was 7.4% and of underweight (low weight for age) 27.5%. Dietary vitamin A intake appeared to be adequate in the children. Intake of vitamin A is predominantly from plant sources. At least 43% of the children consumed the carotene rich red palm oil 6 or more times per week in contrast to less than 1% who consumed eggs or milk for 6 or more times per week. Vitamin A deficiency was low in the children. Only 11.3% of the children had plasma retinol concentration <0.70µmol/L. The results indicate that childhood malnutrition of public health magnitude can coexist with adequate dietary vitamin A intakes or vitamin A status

Africa

Africa is one of the lowest contributors to greenhouse gas emissions causing climate change, yet key development sectors have already experienced widespread losses and damages attributable to human-induced climate change, including biodiversity loss, water shortages, reduced food production, loss of lives and reduced economic growth (high confidence1).// Between 1.5°C and 2°C global warming—assuming localised and incremental adaptation—negative impacts are projected to become widespread and severe with reduced food production, reduced economic growth, increased inequality and poverty, biodiversity loss, increased human morbidity and mortality (high confidence). Limiting global warming to 1.5°C is expected to substantially reduce damages to African economies, agriculture, human health, and ecosystems compared to higher levels of global warming (high confidence).// Exposure and vulnerability to climate change in Africa are multi-dimensional with socioeconomic, political and environmental factors intersecting (very high confidence). Africans are disproportionately employed in climate-exposed sectors: 55–62% of the sub-Saharan workforce is employed in agriculture and 95% of cropland is rainfed. In rural Africa, poor and female-headed households face greater livelihood risks from climate hazards. In urban areas, growing informal settlements without basic services increase the vulnerability of large populations to climate hazards, especially women, children and the elderly. // Adaptation in Africa has multiple benefits, and most assessed adaptation options have medium effectiveness at reducing risks for present-day global warming, but their efficacy at future warming levels is largely unknown (high confidence)./

Dietary habits and metabolic risk factors for non-communicable diseases in a university undergraduate population

Background: Unhealthy dietary patterns are associated with metabolic changes and increased risk of noncommunicable diseases (NCDs), but these associations have not been investigated in representative populations of university undergraduates in low-to-middle income countries (LMICs). Methods: This study was conducted in the three universities in Lagos State, Nigeria to assess the dietary pattern and metabolic risk factors of NCDs among university undergraduate population. Multistage sampling technique was used to select 506 undergraduates from the universities. Pre-tested questionnaire was used to obtain data on sociodemographic characteristics and dietary patterns. Body mass index and metabolic risk factors (abdominal obesity, dyslipidemias, high blood pressure and hyperglycemia) were assessed following standard procedures. SPSS (version 20) was used for data entry and analysis. Association between variables was determined using chi-square and Fisher\u2019s exact tests. Results: The mean age was 20.3 \ub1 3.5 years; 54.7% of them were female. More than one third (37.6%) had no consistent source of income or received less than N10, 000 ($31.7) per month. Less than one third (31.0%) ate three daily meals, 23. 0% ate breakfast regularly, and only 2% consumed the recommended daily amount of fruits and vegetables. Almost half (44.0%) ate pastry snacks daily. Refined rice was the commonest cereal (28.2%) consumed while meat was more commonly consumed daily (32.0%) than milk (14.0%) and fish (10.0%). Twenty-nine (29.0%) and 6.2% of the population daily consumed carbonated soft drinks and alcohol, respectively. Prevalence of abdominal obesity (based on waist circumference) was 5% (1.3% in males and 8.4% in females), dyslipidemias (57.3%), pre-hypertension (8.2%), hypertension (2.8%), and pre-diabetes (1.0%). Obesity was positively associated with consumption of alcohol (\u3c72 = 13.299, p &lt; 0.001). Conclusion: Unhealthy diets and metabolic risk factors of non-communicable diseases are prevalent in the undergraduate population studied. Well-recognized recommendations regarding adequate consumption of fruits, vegetables, fish, and whole grains should be emphasized in a targeted manner in this population. Carbonated soft drinks and alcohol consumption should be discouraged to stem a rising tide of metabolic risk factors for non-communicable diseases among undergraduate students

Walk-Through Energy Audit of An Institutional Building

Improving energy efficiency requires detailed information on energy utilization. Many a times, institutional buildings across developing countries are not energy efficient. Thus, they require quantitative energy consumption audit information. This study outlines daily, weekly and annually projected energy consumption in an academic building within Nigeria. Measurements of the energy utilizations of the building were in accordance to ASHRAE Standard 22, ASHRAE/IES Standard 100-2015 and BCA Health Check report guidelines. Results showed that HVAC appliances and electrical motors driven gadgets consumed 36% and 61.9% of the total energy supplied. In conclusion, improving energy efficiency of similar facilities requires energy conservation practice in terms operating motors and other HVAC devices off idle-time and non-occupancy period respectively

Experimental Investigation of Used Vegetable Oil-Diesel Blends as Alternative to Fossil Fuel in Compression Ignition Engine

Partial replacement of crude oil is required to solve the challenge of depletion of fossil fuel and climate change. Environmental problems occur from the increasing emissions of harmful pollutants and greenhouse gases from the combustion of fossil fuels. Hence, the use of clean energy sources including biodiesel is crucial in this century. In this study, the use of waste vegetable oil blends with diesel (D95B5, D90B10, D85B15, and D80B20) as a retrofit for pure Diesel (D100) was investigated experimentally in a single-cylinder twostroke diesel engine. Engine performance indices such as engine torque, engine power, brake mean effective pressure (BMEP), exhaust gas temperature, volumetric efficiency, air mass flow, fuel mass flow, air/fuel flow ratio, and thermal efficiency were assessed for 8, 16, and 24 ml fuel blends. The volume of fuel blends in the test rig was investigated under constant temperature (34 °C) conditions. Experimental results revealed that the blended fuels worked effectively in the rig and D85B15 gave the best performance within the tested diesel engine. This study established the possibility of partial replacement of pure diesel with fuel blends of diesel and used vegetable oil in internal combustion engine

Biodiesel production from palm olein: A sustainable bioresource for Nigeria

Dangerous environmental consequences and market unpredictability of fossil fuels have necessitated the need for sustainable large-scale production of biofuel in Nigeria. Unrefined palm oil (UPO) is a significant product of commercially available oil palm plants in the country. This study experimentally investigates the production of biodiesel from refined, bleached and deodorised (RBD) palm olein extracted from UPO obtained from batch reactors. The transesterification process of the RBD palm olein with methanol and in the presence of potassium hydroxide (KOH) catalyst produced biodiesel with a 62.5% yield, thus confirming its feasibility for mass production. The derived biodiesel has properties equivalent to ASTM D792 standard for biodiesel fuels