FACULTY OF TECHNOLOGY

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End date: 2009Subject: search.filters.subject.Refrigeration,

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    Duct design and performance: a case study of a University senate chamber
    (2002) Odesola, I. F.; Ndubuisi, C. U.; Ogbolu, N. D.
    This paper present the design of a central air-conditioning /ducting system for a case study of a University Senate Chamber in Nigeria. The design aims at maintaining conditions that are conducive to human comfort within the senate chamber of the University. (24°C - 25.5°C, 50% - 55% RH). The design month was March (6) and using the expert assistance found in the carrier system design ducting analysis manual the refrigeration tonnage obtained was 40 and the total air quantity required to remove the heat load was 9908cfm. Low velocity with equal friction method was used in the ducting analysis. Equipment selection was carried out for the proposed system. A simulation was carried on the proposed system to estimate the relative humidity and temperature at various times. Another test was carried out on the actual (existing unit) to estimate relative humidity and temperature at various times and positions within the chamber. A comparison of the simulated and tested values with standard comfort conditions reveals that the new design will certainly give more comfort.
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    Dynamic modelling of a vapour compression air conditioner system
    (2009) Ajabge, I. O.; Ismail, O. S.
    Modelling is a very important tool for understanding complex problems. A model plays a fundamental role in the analysis, design and development of complex systems, especially when physical testing and experimentation are not feasible - or not possible at all. Modelling technology holds tremendous promise for reducing costs, improving quality, and shortening the time-to-market for manufactured goods. Unfortunately, this technology still remains largely underutilized by industries today, especially in Nigeria. Analyzing vapour compression air conditioners for their capability of achieving a desired performance level is a difficult and essential task that must be undertaken by the specifying engineer. This involves an understanding of what is required for the particular air conditioning application as well as what the particular grouping of equipment components into the system are or, more importantly, are not capable of doing. A detailed dynamic model of a vapour compression air conditioner system is therefore developed. The Model components are mathematically described, considering energy balances within the system. Ambient wet and dry bulb temperature and solar radiation are the few required inputs. Output measures of performance of the system such as system temperatures, energy flows, and coefficient of performance can be predicted. Simultaneously, a software package, "AJBSIM' has been developed to simulate the steady state performance of the equipment, ease and hasten the calculation expedience involved as well as enable parametric studies to be conducted.
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    The development and evaluation of a solar-powered refrigerator using activated carbon/ methanol pair
    (2009) Odesola, I. F.
    A solar-powered adsorption refrigerator using activated carbon/methanol pair was designed and fabricated. The refrigerator has three major components: collector-condenser, and evaporator. A 3 mm thick flat glass was used as flat plate collector. The condenser was made of spirally coiled copper tube immersed in pool of stagnant water contained in a reinforced sancrete tank. The .evaporator was fabricated from standard 15.6 mm diameter copper tubing. The activated carbon used as adsorbent was manufactured locally from shells of a palm kernel. The maximum temperature of 108°C attained in the solar collector was adequate for methanol generation, while maximum received insolation of 1000 kW/m2 was sufficient for methanol desorption. The solar coefficient of performance (COP) of the refrigerator ranged from 0.0339 to 0.0345 compared to 0.03 to 0.055 recorded in the literature. The study shows that a solar powered adsorption refrigerator will operate In Nigeria's tropical climate with satisfactory coefficient of performance.