نشریه مهندسی بیوسیستم ایران
سال پنجاه و دوم شماره 4 (زمستان 1400)

Due to the absence of the sun from sunset to sunrise, the use of energy storage systems is of considerable importance. In this research, a solar pond with a circular cross-section with a diameter of 110 and a height of 120 cm was constructed. In this pond, to extract heat from its lower area, an internal and external heat exchanger was considered, which transferred heat from the solar pond to the consumer by circulating fluid in this area. To receive stable heat, paraffin wax phase change materials were used in the external heat exchanger. The tests were performed and analyzed in two days, without paraffin wax and with it. The thermal discharge period of paraffin wax lasted about 12 hours. To analyze the temperature difference of the external heat exchanger, the data were analyzed using a t-test in two independent groups using SPSS 16 software at a significant level (P

In this research, to breaking the hard woody shell of hazelnuts to obtain the whole and health kernels the conical hazelnut cracker prototype machine with the vertical shaft was designed, constructed, and evaluated. Calculations of the design and manufacturing this machine were performed based on data on the physical and mechanical properties of hazelnuts. The working principle used for this process was based on two coaxial conical shells, which the external shell was fixed on the chassis, and the internal shell named rotor was driven by a vertical shaft. The hazelnut kernels in the space between the two cones in the active area of fracture are affected by the compressive and shear forces and the wood shell is broken and the kernel is removed healthy. Performance evaluation of machine was conducted as a factorial experiment in the form of a CRD with three factors of the moisture content (MC) of hazelnuts in two levels of 5.0% and 8.5% wet basis, the size class (SC) of hazelnut in three levels of small (size < 14 mm), medium (14 mm ≤ size < 16 mm) and large (size ≥ 16 mm), and the rotor rotational speed (RRS) at three levels of 150, 200 and 250 rpm. Results showed that MC and SC have significantly effects on the percent of the intact kernel and the overall losses at the level of 1%, but the RRS had no significant effect on them. In general, the percentage of the intact hazelnuts at 5% and 8.5% MC were 86.1% and 92.1%, respectively. The performance of the hazelnut cracker machine in producing the intact kernel for the size classes of the small, medium, and large was 87.2%, 89.5%, and 90.6%, respectively.

A microwave-hot air dryer with online microwave power density control was developed for banana slice drying in the present study. This dryer consisted of the online mass measurement, imagining unit, and microwave power control circuit systems. The microwave power control system was set with an Arduino board, SSR relay, and control program in MATLAB environment. Experiments with five levels of fixed power density (4, 5, 6, 7, and 8 Wg-1) were done for examining the kinetics of moisture content and microwave power during the drying process. Also, an image processing algorithm was investigated for measuring the burning percentage of banana slices. For modeling of moisture content kinetics, seven mathematical models were nominated. Results showed that the Logarithmic model could predict the drying kinetics of banana slices better than the other models with the highest R2 (0.9966-0.9831) and lowest RMSE (0.01646-0.02679). Also, the trend of microwave power with time for constant remaining the microwave power density during the drying process such as moisture content variation in all experiments was exponential. Quality evaluation of the final product showed that treatments with power densities of 6, 7, and 8 had 12, 24, and 29% burns, respectively, compared to treatments of 4 and 5 without burns.

The purpose of this study was to produce the low fat yogurt using soy protein isolate. The soy protein isolate in concentrations of 0.5, 1.0 and 1.5 was used in low-fat yogurt formulation and the physicochemical properties (pH, acidity, non fat dry matter, syneresis, viscosity) and microbial (growth of mold and yeast) and sensory properties (color, firmness, taste, sourness, spiciness, oldness and moldy and overall appearance) were evaluated on 1, 7, 14 and 21 days of storage. The results showed that with increase in soy protein isolate concentration, acidity, non fat dry matter and viscosity were significantly increased and the yogurt syneresis was significantly decreased, while it had no significant effect on pH (p > 0.05). The most desirable sensory properties were observed in the first days in the control and samples containing 0.5 and 1.0% soy protein isolate (p < 0.05). The results showed that the use of soy protein isolate due to its nutritious compounds can be considered as an offer in the industrial production of functional low fat yogurt.

In this study, the effect of ultrafiltration membrane clarification process on quality indices, bioactive compounds and rheology of pomegranate juice was investigated. For this purpose, after clarification of pomegranate juice by classic method, the juice was treated by ultrafiltration clarification and the effect of operating parameters such as temperature (20 and 30°C) and pressure (1.5, 2.0 and 2.5 bar) on clarity, viscosity, pectin, anthocyanin, phenol, tannin and DPPH radical scavenging activity of pomegranate juice was studied. The results showed that treatments of temperature 20°C and pressure 2 bar and temperature 30°C and pressure 2 bar had the lowest (2.8%) and highest (14.3%) reduction in total anthocyanin, respectively. The treatments temperature 20°C and pressure 2 bar and temperature 30°C and pressure 2 bar had the lowest (6564 mg/L) and highest (5697 mg/L) total phenol content, respectively. The highest reduction of total tannin was observed for treatment temperature 20°C and pressure 2.5 bar (49.7%). The results showed that in all treatments, pectin amount had been reduced over 98% and also, the maximum clarity (96.5%) was observed in sample temperature 20°C and pressure 2.5 bar. In addition, the results showed that an increase in pressure from 1.5 to 2.5 bar led to a significant decrease in viscosity in both temperatures of 20 and 30°C (p < 0.05). Finally, it was concluded that treatment temperature 20°C and pressure 2.5 bar in ultrafiltration membrane clarification are suitable for pomegranate juice clarification.

Cone penetration test is one of the methods widely used for measuring the soil mechanical strength. It can also be used as a simple method to calibrate soil parameters in the discrete element method (DEM) simulations. In this study, a DEM model for the interaction of a cone penetrometer with a clay loam soil was developed and the possibility of finding relationships between the cone index and the parameters of the model for different levels of moisture and soil density was investigated. A hybrid contact model, hysterical spring - linear cohesion was used to simulate the soil. Sensitivity analysis of the model parameters showed cohesion, coefficient of internal friction and particle yield strength are the most important parameters affecting the cone index. Laboratory cone penetration tests using a tension-compression loading frame were performed in remolded soil at two moisture contents of 11 and 16% each at two bulk densities of 1000 and 1150 kg m-3. By fitting the measured and simulated cone index- depth profiles, values ​​for particle yield strength were obtained which showed a strong correlation (R2 = 0.97) with the maximum cone index in the tested soils. The results were validated using plate sinkage test. As a general conclusion, the cone penetration test can be used to calibrate the yield strength of soil particles in the discrete element simulations.