Design and Performance Evaluation of an Indigenous Waste Material Fired Mechanical Dryer Utilizing Outside and Recirculated Air for the Purpose of Waste Heat Recovery

摘要

This paper discusses the results of the research project funded by De La Salle University Research Center on the design, performance evaluation and efficiency test of a mechanical dryer utilizing 100% outside air and another test utilizing outside and recirculated air for the purpose of waste heat recovery. Testing includes drying of agricultural products such as palay, corn and coconut meat using indigenous waste materials namely saw dust, rice husk and charcoal as alternative fuels. Utilization of waste materials as fuel helps waste disposal and collection problems. Performance evaluation consist of the following parameters: Dryer Capacity, Drying Rate, Burner Efficiency, Heating Chamber Efficiency, Drying Chamber Efficiency and Overall Dryer Efficiency. Another important aspect of the study is the quality evaluation of the dried product. Results of the evaluation showed that the utilization of waste heat which is done by recirculating the exhaust air for pre-heating the outside air increases the drying rate and rate of moisture removal in the wet feed. The moisture removal on palay and corn conforms to standard values of 13-16% moisture content of dried product for safe storage and milling especially when charcoal is used as fuel compared with saw dust and rice husk. A software was also developed as a calculation tool to aid the computations and analysis of results. The software was developed based on the Unified Modeling Language (UML) and coded using the Object Oriented Principle of Microsoft Visual Basic 6.0. An advantage of using UML is that, creation of several models can be done simultaneously instead of concentrating on the creation of a single artifact. The development of the software focuses not only on the theoretical principles but also from the user acceptability feedback.