Journal Articles

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Author: search.filters.author.Balaji, Rajoo.Subject: search.filters.subject.Waste heat recovery

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    Optimisation of a waste heat exchanger for ballast water treatment
    (Scientia Iranica B, 2015) Balaji, Rajoo.; Yaakob, Omar.
    Ballast Water Treatment systems, which are type approved and commercially available, require improvements to meet stricter standards, and heat treatment could be a viable additional option. Considering the waste heat potential on a ship, a system harvesting the engine exhaust heat may be envisaged for which a heat exchanger could be vital. Design optimisation of a heater, employing the exhaust gases of an engine as utility fluid, and ballast sea water as the process fluid, was achieved using Lagrangian methods, keeping the annual cost as the objective function. Limiting the number of variables, optimal values were calculated with cost considerations for utility fluid and also pumping costs for utility and process fluids. In all, four optimum designs and three comparative designs were developed. Heat balance data from an operational tanker, specific fuel consumption values and fuel costs were considered for the design. The thermodynamic and geometric designs were worked out using computer based software for a comparison. Designs were compared on the basis of annual cost, optimum exit temperature of shell side fluid, optimum mass flow of tube side fluid and heat exchanger e ectiveness. It is demonstrated that an optimal heat exchanger design can be obtained with simple optimisation procedures.
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    Design verification of heat exchanger for ballast water treatment
    (Jurnal Teknologi, 2014) Balaji, Rajoo.; Yaakob, Omar.; Adnan, Faizul Amri bin.; Koh, Kho King.
    Using waste heat from ship’s engines is one of the methods considered for heat treatment of ballast water. For such a system harvesting the engine exhaust heat, a heat exchanger will be vital. Design optimisation of a heater employing exhaust gases of the engine as utility fluid and ballast sea water as the process fluid was achieved using Lagrangian methods, keeping the annual cost as the objective function. Costs for installation, maintenance as also costs for the utility and process fluids were considered. Heat balance data, specific fuel consumption values from a typical operational ship and current fuel costs were considered for the design. The thermodynamic and geometric designs were worked out using computer based software for comparing the designs. Costs were also computed using a different approach for all the designs. Since the amount of heat transferred was specified and the application was limited to a single process, direct cost method was used for the computation. The objective function values obtained from Lagrangian equations were compared with the values obtained from direct cost computations. From the optimal designs, choice was justified based on annual cost, optimum exit temperature of shell side fluid and optimum mass flow of tube side fluid.
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    Comparision of heat exchanger design for ship ballast water heat treatment system
    (Jurnal Teknologi, 2015-10) Balaji, Rajoo.; Yaakob, Omar.; Koh, Kho King.; Adnan, Faizul Amri bin.; Ismail, Nasrudin bin.; Ahmad, Badruzzaman bin.; Ismail, Mohd Arif bin.; Vern, Yiow Ru.
    Sterilisation by heat can be a capital treatment for ballast water and waste heat from ship’s engines will be a good resource. Based on the waste heat availability on an operational tanker, a ballast water treatment system was envisaged including a shipboard heat exchanger for waste heat recovery. To verify the heat availability and the species’ mortalities, test rigs were arranged similar to shipboard arrangement. For assessing the smaller heat exchangers for the tests, designs were developed using Bell-Delaware approaches based on the shipboard heat exchanger design. The thermodynamic and geometric values were computed and the features of the commercially available and fitted heat exchangers were compared with the developed designs. Two commercially procured heat exchangers fitted on two separate engine test rigs were used for tests. The designs of commercially procured heat exchangers were close to the developed designs and were found to be suitable for the tests planned.