Propane (HC – 290) as an Alternative Refrigerant in the Food Transport Refrigeration Sector in Southern Africa – a Review

This research articles was published in Journals Automotive Experiences Volume Volume. 5 No.1,2022Most of the food transport trucks in Sothern Africa are equipped with refrigeration and air conditioning systems filled with fluorocarbon refrigerants such as R404A to facilitate the heat transfer process. These refrigerants are synthetic chemicals and have high potential to cause global warming and damage to the ozone layer. Currently, natural refrigerants are considered as alternatives to these man-made refrigerants to mitigate some of the environmental risks. The natural refrigerants are the substances that occur in nature such as hydrocarbons (HC), ammonia, and carbon dioxide. These type of refrigerants have been in the market for many years, but in some applications such as domestic refrigerators, heat pumps, chillers, and air conditioners, whereas fluorocarbons are the mostly used in the food transport refrigeration systems. Natural refrigerants such as propane (HC – 290) are now penetrating the market in food transport refrigeration systems where previously fluorocarbons were the favoured option. Therefore, this work reports the possibilities of using non-fluorinated hydrocarbon/natural refrigerant (propane – R290) in the food transport refrigerated systems in Southern Africa; a case study of South Africa. R290 has the potential to lower greenhouse gases emissions compared to hydrofluorocarbons (HFCs) which are widely used in most of the existing food transport refrigeration systems in South Africa. R290 has negligible Global Warming Potential (GWP) of 3 which is well below the global threshold value of 150. The review revealed that refrigeration capacity of R290 is in the average of 10 – 30% higher than commonly used fluorocarbon refrigerants such as R404A and R134A. Since R290 is labeled as a flammable refrigerant, the present study also reviews its flammability safety measure

Storage and thermal stability of biodiesel produced from manketti nut oil of Southern Africa origin with the infuence of metal contaminants and antioxidants

This research article published by Springer Nature Switzerland AG., 2020Biodiesel has widely been produced from common edible oils; however, food versus fuel conficts has motivated researchers to search for other less common feedstock for production of biodiesel. Thus, this study investigates the suitability of biodiesel made from less common manketti nut oil in terms of its thermal and long-term storage stability. Also, since biodiesel is stored in containers made of diferent metals; the infuence of metal contaminants on the storage stability of biodiesel is also examined. Manketti Oil Methyl Ester (MOME) is synthesized by the transesterifcation process and characterized as per biodiesel global standards. MOME is doped with antioxidants (1, 2, 3 tri-hydroxy benzene (Pyrogallol, PY) and 3, 4, 5-tri hydroxy benzoic acid (Propyl Gallate, PG)) at diferent ratio to analyse its infuence on the stability of MOME. Also, 2 ppm of selected metals (Co, Cu, Fe, Mn, and Ni) is doped to MOME samples with and without antioxidants and stored for 6 months in open and closed 500 ml plastic bottles. Oxidation stability is measured once a month to monitor stability of MOME. Thermogravimetric analysis is conducted to examine thermal stability of MOME. The results show that freshly-synthesized MOME has oxidation stability of 4.24 h below the European EN 14214 (8 h) and South African SANS 1935 (6 h) standards. On adding antioxidant PY and PG at 200 ppm concentration, the oxidation stability increases to 13 h and 8.5 h respectively. The result of MOME contaminated with metals shows that Cu has the highest damaging efects on oxidation stability during storage. Additionally, thermal stability analysis results exhibit that MOME has excellent thermal stability of 211.33 °C

Viability of non-edible oilseed plants and agricultural wastes as feedstock for biofuels production: A techno-economic review from an African perspective

This research articles was published in Journals Biofuels Bioproducts& Biorefining Volume 17, Issue 5,2023Given the benefits of biofuels over conventional fuels, there is concern that widespread production of biofuels from edible feedstocks to meet demand will lead to food insecurity and other socioeconomic challenges. Thus, the goal of this research is to look into the techno-economic potential of non-edible oilseed plants and agricultural wastes as primary feedstocks for biofuel production in Africa. The inability of biofuel to cope in the fuel market has been demonstrated to be due to the high production costs, which limit profitability because the end price is heavily influenced by that of conventional fuel. However, the high production costs are entirely due not only to components such as feedstock, conversion processes, and infrastructure but also to a lack of techno-economic assessment (TEA). African biofuel production can be competitively industrialized through the adoption of strong supportive policies and programs. Adoption of these policies and programs is critical for capitalizing on the benefits of non-edible feedstocks in biofuel production while also boosting rural development through job creation. Techno-economic assessment of conversion processes and infrastructure is recommended to provide a clear picture of the techno-economic aspects, serving as a blueprint for the design of biofuel production facilities. Further, TEA has been shown to be a useful tool in the development process of new technologies aimed at lowering overall production costs and making biofuel more affordable. The combination of TEA and enabling policies and programs will increase the price competitiveness of biofuels, allowing them to capture a sizable share of the fuel market. © 2023 Society of Industrial Chemistry and John Wiley & Sons Ltd

Influence of metal contaminants and antioxidant additives on storage stability of biodiesel produced from non-edible oils of Eastern Africa origin (Croton megalocarpus and Moringa oleifera oils)

This research article published by Elsevier Ltd., 2015The effect of metal contents and antioxidant additives on the storage stability of biodiesel produced from less common non-edible oils of Eastern Africa origin (Croton megalocarpus and Moringa oleifera) were evaluated and reported in the present study. The croton oil methyl ester (COME) and moringa oil methyl ester (MOME) were produced by transesterification process. The fuel related properties were determined as per EN 14214 and ASMT D6751 global biodiesel standards. The fresh produced COME and MOME without any additives displayed oxidation stability of 2.5 h and 5.3 h respectively. The oxidation stability of COME did not meet the minimum requirement prescribed in ASTM D6751 and EN 14214 standards of 3 h and 6 h respectively because it was rich in linoleic methyl esters (70.5%) which are prone to oxidation. However, MOME met the minimum requirement of ASTM D6751 but not the EN 14214. In order to improve the storage stability of COME and MOME, two most effective synthetic antioxidants as reported in the literature (1,2,3 tri-hydroxy benzene (Pyrogallol, PY) and 3,4,5-tri hydroxy benzoic acid (Propyl Gallate, PG)) were doped to the biodiesel samples to examine its effectiveness. Also, the samples with and without antioxidant were mixed with different transition metals (Fe, Ni, Mn, Co and Cu) to evaluate the impact of these metals on storage stability of COME and MOME. The samples were stored indoor for 6 months in completely closed and open translucent plastic bottles, the oxidation stability were measured every month. The results showed that, the antioxidant PY was more effective than PG. Fe displayed least detrimental effect on oxidation stability of COME and MOME while Cu had great detrimental impact. The samples in the completely closed (air-tight) bottles recorded higher oxidation stability compared to the ones kept in the open bottles because were exposed to air which enhanced the oxidation of the samples

Tamarindus Indica fruit shell ash: a low cost and effective catalyst for biodiesel production from Parinari curatellifolia seeds oil

This research article published by Springer Nature Switzerland AG., 2019The study evaluated the potential use of agricultural waste, Tamarindus indica fruit shell ash, as a solid base catalyst for production of biodiesel. The catalyst was prepared by calcination of T. indica fruit shell at 800 °C in mufe furnace for 3 h. Branauer-Emmett-Teller, thermal gravimetric analysis, X-ray difraction, scanning electron microscope, X-ray forescence, and Hammett indicator techniques were used to characterize the physicochemical properties of the produced catalyst. The catalyst had basic strength of greater than 9.7 and mesoporous structure with pore size d=3.2 nm. The crystalline phase was made up of calcium oxide, potassium oxide, and magnesium oxide. The catalyst was tested for biodiesel production using Parinari curatellifolia seeds oil. The results showed that the best operating parameters for the production of biodiesel were 9:1 methanol to oil molar ratio, 125 mg catalyst (5 wt% of oil), 2 h reaction time, and 60 °C reaction temperature. These optimized operating parameters aforded a maximum yield of 96.2%. Also, fuel properties of biodiesel: acid value, viscosity, and fash, pour, and cloud points were investigated and compared to the ASTM standards limits D6751. The results were observed to be in good agreement with the ASTM standards limits for biodiesel. In addition, the catalyst was easily separated and subsequently reused for four runs in biodiesel production. Thus, Tamarind fruit shell derived catalyst is very promising for the production of biodiesel due to its high performance, low-cost, easy preparation and availabilit

An Analysis of Fuel Properties of Fatty Acid Methyl Ester from Manketti Seeds Oil

This research article published by Taylor & Francis Online, 2014The fatty acid methyl esters (FAME)produced from vegetable oils, animal fats, or waste oils known as biodiesel has attracted attention as possible replacement of fossil fuels. The fuel properties of biodiesel are similar to that of conventional petro-diesel and it is more environmentally friendly. This study investigated in detail the fuel properties of biodiesel from less common edible oil produced from Manketti seeds (Schinziophyton rautanenii). Manketti Oil Methyl Ester (MOME) was produced by transesterification process using an alcohol in the presence of a catalyst. The fuel related properties of MOME were determined and compared with the global biodiesel standards such as ASTM 6751 and EN 14214. Also, the effects of different antioxidants; 1, 2, 3 tri-hydroxy benzene (Pyrogallol, PY), 3,4,5-tri hydroxy benzoic acid (Propyl Gallate, PG) and 2-tert butyl-4-methoxy phenol (Butylated Hydroxyanisole, BHA) were investigated on oxidation stability, kinematic viscosity and cetane number (CN) of MOME. The results showed that, most of the determined fuel properties fulfilled the minimum requirement of global biodiesel standards. Among antioxidants used in this study, PY and PG were more effective compared to BHA on oxidation stability. Also, addition of antioxidants on MOME showed positive results on CN which was increased and kinematic viscosity was decreased. In summary, biodiesel produced from manketti seeds oil indigenous to Southern Africa can be used as partial substitute of mineral diesel

Design and Performance Analysis of Composite Airfoil Wind Turbine Blade

Abstract Small horizontal axis wind turbine rotors with composite airfoil rotor blades were designed and investigated in the present study in order to improve its performance in low wind speed and low Reynolds number (Re) conditions for standalone system. The geometrical and aerodynamic nature of a single airfoil small horizontal axis wind turbine blade curtails efficient energy harnessing of the rotor blade. The use of composite airfoil rotor blade improves energy production but imposes uncertainty in determining an optimal design angle of attack and the off design aerodynamic behaviour of the rotor. This research investigated the effects of two airfoils used at different sections in a composite blade and determined the blade’s optimal design angle of attack for maximum power generation. The wind turbine rotor blades were designed using blade element momentum (BEM) method and modelled by SolidWorks software. The SG6042 and SG6043 airfoils were used for the composite airfoil blades. Five wind turbines were designed with rotor blades of design angles of attack from 3° to 7°. The five wind turbine blades were simulated in computational fluid dynamics to determine the optimal design angle of attack. The composite airfoil wind turbine blade showed improved performance, whereas, the wind power generated ranged from 4966 W to 5258 W and rotor power coefficients ranged from 0.443 to 0.457. The blade with design angle of attack of 6° showed highest performance. Keywords: composite airfoil, lift-to-drag ratio, pressure coefficient, Reynolds number, design angle of attack

Mungongo Seeds Oil (Schinziophyton rautanenii) as a Potential Source of Bio-Diesel

This research article published by Scientific.Net, 2014Biodiesel from mungongo seeds oil (Schinziophyton rautanenii) was investigated in the present study to determine its suitability for use as substitute of petro diesel. The fuel properties of Mungongo Oil Methyl ester (MOME) such as cetane number, kinematic viscosity, oxidative stability, lubricity, cloud point, pour point, cold filter plugging point, flash point, acid value, density, higher heating value, free and total glycerol were determined and compared with global biodiesel standards such as ASTM 6751 and EN 14214. Most of the determined fuel related properties of MOME fulfilled the minimum requirements of ASTM D6751 and EN 14214 biodiesel standards except oxidation stability. The stability of biodiesel is very critical and biodiesel requires antioxidant to meet storage requirements and to ensure fuel quality at all points along the distribution chain. Therefore, three antioxidants; 1, 2, 3 tri-hydroxy benzene (Pyrogallol, PY), 3, 4, 5-tri hydroxy benzoic acid (Propyl Gallate, PG) and 2-tert butyl-4-methoxy phenol (Butylated Hydroxyanisole, BHA) were investigated. The result showed that, PY and PG were more effective antioxidants than BHA

A review on opportunities for the development of heat pump drying systems in South Africa

This research article published by the South African Journal of Science, 2014Recently, it has been discovered that heat pump drying is an efficient method of drying for drying industries. Heat pumps deliver more heat during the drying process than the work input to the compressor. Heat pump drying is a more advanced method than the traditional South African industrial and agricultural drying methods, such as direct/indirect sunlight, wood burning, fossil fuel burning, electrical heating and diesel engine heating. Heat pump dryers provide high energy efficiency with controllable temperature, air flow and air humidity and have significant energy-saving potential. In the last decade the market for heat pump systems for water heating and space cooling/heating has grown in South Africa, but the development of heat pumps for industrial and agricultural drying is very slow. As a result of high increases in fossil fuel prices and electricity in South Africa, as well as the problem of CO2 emissions, green energy, energy saving and energy efficiency are imperative. The development of heat pump drying systems in South Africa is an efficient way to solve energy problems in drying applications as this technology is still in its infancy. We review studies on heat pump drying and compare the methods therein with the most common methods of drying in South Africa

Effects of different supplementary cementitious materials on durability and mechanical properties of cement composite – Comprehensive review

This research articles was published in Journals Heliyon Volume 9, ISSUE 7, 2023Ordinary Portland cement is the highest produced cement type in the world, however its pro- duction is high energy consumption means expensive, huge natural resource consumptive, and creating high environmental pollution. Hence many researchers studied to reduce the effect of ordinary Portland cement by substituting artificial and natural supplementary cementitious materials (SCMs) commonly in a concrete/mortar mixture. However, the comprehensive effect of different SCMs on various properties of cement composite materials are not well known. So the present study sought to review the effect of different natural and artificial SCMs on the durability and mechanical properties of cement composites, especially due to their doses, types, chemical composition, and physical properties. Hence the review shows that many SCMs used by literatures from different places satisfy ASTM replacement standard based on their chemical compositions. Also, the review indicated as adding 5–20% of different SCMs positively affect mechanical properties, durability, and microstructures of the cement composite materials, specifically as most researchers found isolately adding of 15% SCMs such as bentonite, kaolin, and biomass, 20% addition of volcanic ash and 10% employment of fly ash, silica fume, and zeolite to the cement composites achieves the most optimum compressive and split tensile strength. These observations reveal that most natural pozzolana can more replace cement to give optimum strength, hence can more reduce energy consumption, production cost, and environmental pollution comes due to cement production. Furthermore, most researchers found employing different SCMs generally improves durability, however there is a limited study on the effect of silica fume on water ab- sorption and acidic attack resistance of cementitious materials. Therefore, it is recommended that future research should also focus more to know the effect of silica fume on the durability of cement composites