Bukola Bolaji | Federal University Oye-Ekiti (original) (raw)

Papers by Bukola Bolaji

Maǧallaẗ al-abḥāṯ al-handasiyyaẗ, 2013

In this study, the performance simulation of some hydrocarbon refrigerants (R290, R600 and R600a)... more In this study, the performance simulation of some hydrocarbon refrigerants (R290, R600 and R600a) as alternatives to R134a in refrigeration system with sub-cooling is conducted by thermodynamic calculation of performance parameters using the REFPROP software. The results obtained showed that the saturated vapour pressure and temperature characteristic profiles for R600 and R600a are very close to that of R134a. The three hydrocarbon refrigerants exhibited very high refrigerating effect and condenser duty than R134a. The best of these parameters was obtained using R600. The discharge temperatures obtained using R600 and R600a were low, while that of R290 was very much higher. The highest coefficient of performance (COP) and relative capacity index were obtained using R600. Average COPs of R600 and R600a are 4.6 and 2.2% higher than that of R134a, respectively. The performances of R600 and R600a in system were better than those of R134a and R290. The best performance was obtained usin...

International Journal of Sustainable Energy, 2010

The design and construction of a refrigerator as a test rig, in investigating the performance of ... more The design and construction of a refrigerator as a test rig, in investigating the performance of Liquefied Petroleum Gas (LPG), which has zero ozone depleting potential and very low global warming potential, as working fluid in vapour compression refrigerating system as a possible alternative. The design was made with these assumptions:(a) steady state operation; (b) no pressure loss through pipelines,; (c) heat losses or heat gains from or to the system are neglected and of 75% isentropic efficiency. The following heat sources are considered: transmission load,qt= (A)(U)(∆T), infiltration load, qa= ma(ho – hi), product load, qpa= (m)(c)(∆T), specific heat given off by the product in freezing, qf = mLf,, quantity of heat given off by the product in cooling from its freezing temperature to the final storage temperature, qpb= (m)(c)(∆T), light Load, qL= Light rating(W) x Time(S). The total cooling load capacity of the refrigerator was obtained summing the various sources of heat into ...

Journal of Sustainable Energy and Environment, 2011

In this paper, the performances of three ozone-friendly Hydrofluorocarbon (HFC) refrigerants (R32... more In this paper, the performances of three ozone-friendly Hydrofluorocarbon (HFC) refrigerants (R32, R134a and R152a) in a vapour compression refrigeration system were investigated experimentally and compared. The results obtained showed that R32 yielded undesirable characteristics, such as high pressure and low Coefficient of Performance (COP). Comparison among the investigated refrigerants confirmed that R152a and R134a have approximately the same performance, but the best performance was obtained from the used of R152a in the system. As a result, R152a could be used as a drop-in replacement for R134a in vapour compression refrigeration system. The COP of R152a obtained was higher than those of R134a and R32 by 2.5% and 14.7% respectively. Also, R152a offers the best desirable environmental requirements; zero Ozone Depleting Potential (ODP) and very low Global Warming Potential (GWP).

The paper focuses on solid waste management in Nigerian cities with particular attention to Lagos... more The paper focuses on solid waste management in Nigerian cities with particular attention to Lagos and Ado-Ekiti cities. It has critically examined the waste storage methods, frequency of wastes collection and waste disposal methods in both cities. Research findings show that solid waste collection and disposal should be on daily basis in the highly commercialized cities, while in the less commercialized cities, solid waste collection and disposal can be carried out on weekly basis. The waste disposal methods such as open dumps, emptying waste into water bodies which pose great hazard to human, animal and plant lives are commonly practiced in Nigeria, while less hazardous methods such as disposal through incineration and sanitary landfill are less employed.

This paper examines sources of air pollution and strategies for its management in the urban citie... more This paper examines sources of air pollution and strategies for its management in the urban cities. ‎Emphasis is laid on industrial air pollution and vehicular emission, which are the major urban air ‎polluters. Various gases that are emitted by industries into the atmosphere near and around ‎dwelling places were analyzed. Also analyzed is the combustion of large quantity of ‎transportation fuels in the urban cities, which releases several contaminants into the atmosphere. ‎These contaminants include carbon monoxide, hydrocarbons, oxides of nitrogen, lead and other ‎particulate matter. Various strategies which can be employed for the management of urban air ‎pollution were discussed, covering stack monitoring, changing process operation and cleaning ‎flue gases for industrial emissions, and changing fuel type, removing gross polluters, cleaning ‎vehicle exhaust gases and traffic management for vehicular emissions.‎

International Journal of …, 2010

A rice de-stoning machine using vibrating sieves was designed, fabricated with locally sourced ma... more A rice de-stoning machine using vibrating sieves was designed, fabricated with locally sourced materials and tested. The performance of the machine was evaluated and the results obtained showed that the feed regulator opening has significant effects on the de-stoning rate, de-stoning efficiency and rice losses. The best performance was obtained at feed regulator opening of 20 mm. Above 20 mm opening, the higher the feed regulator opening the higher the de-stoning rate and grain losses, and the lower the de-stoning efficiency. The average capacity of the machine was found to be 31.84 g/sec. and the average efficiency also was 98.3%.

The effect of heat transfer medium (HTM) on the environment is associated with ozone layer deplet... more The effect of heat transfer medium (HTM) on the environment is associated with ozone layer depletion and global warming. The role of HTM (working fluid) in the heating and air conditioning industries is paramount, which cannot be underestimated. The conventional refrigerant has been predominantly used over decades due to their thermodynamic properties. However, hydrocarbon refrigerants such as isobutane are considered substitutes because they have negligible global warming potential and zero ozone depletion. That makes it eco-friendly among other existing refrigerants. The investigation of the refrigeration system's performance characteristics required consideration for the coefficient of performance, refrigerating effect, and the compressor work; this enables the determination of the system's efficiency without any assumption. Another factor that suggests a better absorption of refrigerant (working fluid) into a refrigeration system is an increase in the coefficient of performance (COP). The effect will cause a reduction in the rate of energy consumption by the compressor. The result shows that the system's coefficient of performance when using R600a was 27.1% higher than when working with R134a, with an energy reduction of 23.3%.

The collector efficiency of a thermosyphonic solar water heating system was investigated theoreti... more The collector efficiency of a thermosyphonic solar water heating system was investigated theoretically and experimentally. Mathematical models were developed and used to predict the system performance. The solar collector with water pipes spreading across its width was also developed , tested and the theoretical results obtained agreed well with the experimental results. The collector efficiency is high especially around midday when the solar collector receives the highest energy. The results also reveal the dependency of the system performance on intensity of solar radiation and mass flow rate. Increase in both solar radiation and mass flow rate increases the collector efficiency. Maximum ef-ficiencies of 72.8 and 70.4% were obtained from theoretical and experimental analyses, respectively, at optimum mass flow rate of 0.098 kg/s.

Alternative refrigerants Ozone depleting R22 R429A R435A R457A A B S T R A C T Ozone depletion an... more Alternative refrigerants Ozone depleting R22 R429A R435A R457A A B S T R A C T Ozone depletion and global warming are presently the most serious global environmental problems and they have led to drastic changes in the refrigeration technology. Therefore, environment-friendly refrigerants have attracted a significant attention. This paper presents the thermodynamic study of non-ozone depleting R429A, R435A and R457A refrigerants as substitutes for R22 in airconditioning systems. The results obtained showed that the vapour pressure curves of R429A, R435A and R457A are very close to that of R22 with advantage of lower deviation in pressure. These refrigerants also exhibited lower pressure ratio and discharge pressure than R22 and their average discharge temperatures are 24.03, 13.54 and 28.53 % respectively lower than that of R22. They showed higher coefficient of performance than R22 with the average values of 2.47, 3.96 and 2.98 % respectively higher which shows better efficiency. T...

ASSET:An International Journal of Agricultural Sciences, Science, Environment and Technology (Series B), 2007

The effects of annealing on the mechanical properties of strain hardened coiled-rolled wire of lo... more The effects of annealing on the mechanical properties of strain hardened coiled-rolled wire of low carbon steel, which is used for manufacturing barbed wire, office pins, nails and fencing were investigated in this paper. The as-received coiled-rolled wire was strain-hardened by drawing it through drafts of 30.56, 55.56, 75.00 and 88.89%, respectively. This was followed by process annealing at 400, 500 and 650 0 C. The tensile strength, yield stress, hardness, percentage reduction in area and percentage elongation of the annealed specimens were evaluated and compared with values for commercial specimens. The results obtained showed that NS 34 LC rolled coiled wire attains its full hardness or full brittleness at 88.89% strain hardening. It was observed that for optimal mechanical properties of cold worked coiled wire of the low carbon steel, the material should not be strain hardened beyond the drawing of 75% draft and should be critically annealed at 650 0 C for soaking time of...

Journal of the Nigerian Association of Mathematical Physics, 2011

The dynamic behaviour of a simply supported rectangular plate is studied. This research work is b... more The dynamic behaviour of a simply supported rectangular plate is studied. This research work is based on the theory of the orthotropic plate simply supported on two sides and free on two other sides. The plate is excited by a moving load while the dynamic response of the structure was obtained using the classical double Fourier series expansion technique, which satisfies the boundary conditions at the four edges. In the absence of the external excitation, the vibration yields free frequencies, other wise, forced frequency is produced. The results obtained from the numerical example are in agreement with the ones in the existing literatures. In addition, the effects of variations in flexural rigidity and that of the frequencies of vibrations are also presented. Keywords: dynamic, rectangular plate, classical, frequencies Journal of the Nigerian Association of Mathematical Physics , Volume 19 (November, 2011), pp 183 – 192

Journal of Energy Technologies and Policy, 2018

Solar energy is the most promising among the available green energy sources and also the remedy t... more Solar energy is the most promising among the available green energy sources and also the remedy to the increasing global warming potential and ozone depletion. This paper presents an experimental evaluation of an adsorption refrigeration system uses solar energy as a source of heat gain to drive the refrigeration system. It consists of a solar collector, an adsorbent bed, a condenser and an evaporator. The effect of variation of the ambient, condenser, evaporator and desorption temperatures on the COP system and SCP cycle with local weather parameters were investigated. A parabolic solar concentrator was built to collect the solar energy to heat the combination of adsorbent, Activated carbon and adsorbate, methanol and the system employed solar energy as the main power supply. The experimental results revealed that the ambient, condenser, evaporator and desorption temperatures were increased by 25%, 4%, 13% and 265% respectively with solar time from 9hr to 13hr. The response of COP ...

IOP Conference Series: Earth and Environmental Science, 2019

This paper presents performance analysis of a domestic refrigeration system using R600a as refrig... more This paper presents performance analysis of a domestic refrigeration system using R600a as refrigerant. Investigation was conducted experimentally to select an appropriate refrigerant mass charge for the system and to compute the cooling system performance characteristics under ambient temperature of 29°C. The choice of the hydrocarbon refrigerant (R600a) became so imperative due to notable influence of chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs) on global warming and ozone depletion. UNFCCC and Montreal Protocol regulation have banned the use of halogenated refrigerants in cooling and heating systems. The paper reveals that the power consumed by the system using mass charge of 15 g refrigerant was reduced by 9.3 and 10.9% compared with the 10 and 25 g refrigerant mass charges respectively. In addition, the results show that the coefficient of performance (COP) of the refrigeration system while working with 15 g is 24.7 and 20.2% higher...