Drying Kinetics of Natural Rubber Sheets by Using a Hybrid Solar-Electric Dryer with Force Convection

AbstractIn this work, a hybrid solar-electrical dryer was constructed for studying the drying kinetics of natural rubber sheets. This system composed of the solar collector, which used to collect heat from the sun light. The hot air from solar collector was sent to the drying chamber, where an auxiliary heater can increase the temperature in the drying chamber in order to control the drying temperature. The rubber sheets were dried at the controlled temperature 40 50 and 60 °C. The moisture ratio of rubber sheets drying was investigated.  Seven models were tested to fit with the experimental data. A modified Henderson and Pabis model was the best of curve fitting of  the drying behavior of rubber sheets in these specific experimental conditions. Finally, the consumptions of electrical energy and solar energy were determined, which is found in the range of 15-32% of the solar energy used.

Design and analysis of a doubly corrugated filter for a combined multi-feed microwave-hot air and continuous belt system

A doubly corrugated filter was designed for a combined multi-feed microwave-hot air and continuous belt system (CMCB). The proposed filter reduces microwave energy radiation from the open entry of the continuous belt system. Microwave radiation leakage that affects a human should remain below 10 mW/cm2. The filter was designed for stop-band frequency range 2,300-2,600 MHz, while the operating frequency is 2,450 MHz, and for attenuation greater than 60 dB in this range. We report on optimizing all the design parameters of a doubly corrugated filter and on experimental verification after its installation at the Research Center of Microwave Utilization in Engineering (R.C.M.E) at Thammasat University, Thailand

Characterization of bio-oil production by microwave pyrolysis from cashew nut shells and Cassia fistula pods

In this study, the production of bio-oil by pyrolysis with microwave (MW) heating was tested experimentally. Two magnetrons with a total MW power of 1,600 W were used in the pyrolysis setup. The electric field strength was 185.38 V·m−2 at an MW frequency of 2.45 GHz. Cashew nut shells (CNS) or Cassia fistula pods (CFP) were pyrolyzed at 400°C, 500°C, or 600°C, with biomass-to-activated carbon ratio set at 70:30, 80:20, or 90:10. The largest yield of bio-oil was found for CNS at 600°C, and for CFP at 500°C, both with 90:10 ratio, achieving, respectively, 20.0% and 15.8% yields. When the bio-oil yields from CNS and CFP at 90:10 ratio and 400–600°C were analyzed with gas chromatograph-mass spectrometer, the components found included acids, esters, ketones, furans, pyrans, guaiacol, syringol and phenols, and phenolic derivatives were the dominant type of compounds. There were 23.56% and 13.23% phenolic derivatives, respectively, in the bio-oils from CNS (at 500°C) and from CFP (at 400°C). An analysis with Folin–Ciocalteu reagent of the phenolic contents in bio-oils gave the respective ranges 146.83–164.83 mg·GAE·g·DW−1 and 39.34–45.91 mg·GAE·g DW−1 for CNS and CFP (both run with 90:10 ratio)

Properties of Bio-oil and Bio-char from High-intensity Microwave-assisted Pyrolysis of Oil Palm Shell Waste

Microwave-assisted pyrolysis was applied using four magnetrons to implement a high intensity at a power density of 0.3 × 107 W/m3 with 800 g specimen size. The 23 full factorial experimental design manipulated the factors temperature, mixture ratio, and pyrolysis time, seeking to maximize %yield at minimum cost of crude bio-oil. The optimum according to model fit had a temperature of 611 °C with a 70:30 sample mixture ratio of oil palm shell (OPS) to activated carbon (AC), and time 39.6 min for a yield of 15.3% and 8.48 Thai-Baht/cc cost. The coefficients of determination were R2 = 93.99% and 94.00% for the respective models. In the aqueous phase of crude bio-oil, acetic acid was the dominant chemical component at 55.2%, whereas phenol was dominant in the bio-oil phase at 44.2%, from 400 °C pyrolysis temperature. The assessed properties of bio-char were proximate composition, heating value, specific surface, and pore volume, and these were improved compared to the raw OPS. However, these properties must be improved further to match commercial-grade activated carbon