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Author: Gottschalk, Klaus × Publisher: Amsterdam : Elsevier ×

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    Energy interaction of sub processes in drying value chain using exergy waste. Study case: drying and greenhouse growing of tomato
    (Amsterdam : Elsevier, 2014) Ramireza, Tundra; Measa, Yunny; Gottschalk, Klaus
    In the drying value chain for fruits and vegetables, nine sub-processes have been identified. This work analyses the interaction between growing in greenhouses and drying sub processes for exergy and water flow reutilization. By thermodynamic model simulation, wet air from drying process is retrieved back to the crops within greenhouses. This interaction is an economic solution for the problem of high temperatures and low relative humidity within the greenhouses in hot dry environments. Humidity after the drying is quantified to estimate exergy profiles. Results are an average decrease of temperature of 12.8 °C and 8.7 °C and an increment of relative humidity of 7% and 9%, for different day conditions.
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    Mathematical model for a heat pump dryer for aromatic plant
    (Amsterdam : Elsevier, 2013) Hossain, Mohammed Ayub; Gottschalk, Klaus; Hassan, Mohammad Shoeb
    A mathematical model was developed to evaluate the performance of heat pump dryer for drying of aromatic plants. The model consists of three sub-models; namely, drying model, heat pump model, and performance model. Drying model was developed based on mass balance, heat balance, heat transfer and drying rate equations. Heat pump sub-model consists of some theoretical and empirical equations for estimating the parameters of evaporator, compressor, condenser and expansion valve. The performance sub-model was the equations for prediction of drying efficiency, COP (coefficient of performance), MER (moisture evaporating rate) and SMER (specific moisture evaporating rate). The model was validated with the experimental data. The experiments was conducted in a fixed bed drying of valerian roots (Valeriana officinalis L.) in cooperation with a agricultural company (Agrargenossenschaft Nöbdenitz e.G., Thüringen) in Thüringen, Germany. Data logger was used to record the temperature, relative humidity, humidity ratio and enthalpy of air at different positions of the dryer equipped with different types of sensors. The average drying air temperature was 36.84°C and relative humidity was about 20%. About 89 hours were required to reduce the moisture content of valerian roots from 89 to 9% (wb). The simulated results (temperature, relative humidity and moisture content) agreed well with the experimental results. The average COP, MER and SMER and drying efficiency were 5.45, 140.03 kg/h, 0.038 kg/kWh, and 78.23%, respectively. This model may be used for design data for heat pump dryer for drying of aromatic plants as well as other heat sensitive crops.