Improved rotary film evaporator for concentrating organic fruit and berry puree

This paper reports the improved rotor-film evaporator with the lower arrangement of the separating space, the auger-type discharge of concentrated organic fruit and berry paste, and preheating the puree with secondary steam. The working surface of the evaporator is heated by a flexible film resistive electric heater of the radiating type with an insulating outer surface. Peltier elements installed in the device make it possible to provide low-voltage power for exhaust fans from the thermal secondary steam. The puree fed for processing is preheated by 8...10 °С by the heat from the concentrated product and secondary steam. For the experiment, fruit and berry blended puree from apples, quince, and black currants was used. The structural and mechanical properties of blended puree have been determined when the temperature changes within 55...75 °С, in particular, the effective viscosity varies in the range of 22...6 Pa∙s, the maximum shear stress ‒ 29...8 Pa. Effective regions in the fruit and berry puree concentration process have been established: Kmin=Vpaste/Vpuree=0.190; Kmax=Vpaste/Vpuree=0.725 When concentrating fruit and berry pastes with an initial solids content of 9...15 % to the resulting content (29...31 %), it is advisable to apply a surface load of 0.048...0.121 kg/m2s. By calculation, the reduction of the specific energy consumption for heating the volume of the product unit has been confirmed: a rotor-film evaporator – 547 kJ/kg over a period of 75 s, compared to the basic vacuum evaporator – 1,090 kJ/kg, respectively, over 1.08 hours. The results could be useful when designing evaporating equipment for rotor-film-type devices in order to concentrate various blends of fruit and berry raw materials under conditions of using the energy of secondary steam.

Technological breakthrough of the agrarian-and-food innovations in dairy case for example of universal agricultural raw materials. Reverse osmosis

Aim. Consideration of the membrane technology process – reverse osmosis – by directed and controlled processing of whey and its filtrates through special semipermeable partitions (filter membranes) with a pore size from 0.1 to 1.0 nm, carried out at a pressure of 3.0 - 10.0 MPa with the release of particles (cutting off) with a molecular weight of 100 Daltons. Reverse osmosis allows you to concentrate all the compounds of whey and filtrates, separating almost distilled water (condensate). Discussion. In the molecular sieve separation system, reverse osmosis logically continues the membrane treatment of filtrates (permeates) of native, as well as separated whey and their microfiltrates, ultrafiltrates, nanofiltrates and diafiltrates. In principle, the reverse osmosis process should be implemented to pre-concentrate the whey, which will eliminate its loss (draining) and expand the range of use. OO is promising for processing salted whey with the removal of unwanted sodium chloride, as well as for cleaning the condensate of evaporation plants from the components of dairy raw materials that come with foam and secondary steam. Conclusion. In general, for the dairy industry of the food industry of the agro-industrial complex, reverse osmotic treatment is necessary for the implementation of a closed production cycle with a recycled water supply.

Thermodynamic Analysis and Optimization of Secondary Overheating Parameters in Turbo-Expander Plants on Low Boiling Working Fluids

The paper presents a thermodynamic analysis of secondary overheating in turbo-expander plants on low-boiling working fluids. The possibility of optimizing the parameters of the working fluid in a secondary stem superheater has been studied. The research was carried out for two typical turbo-expander cycles: with a heat exchanger at the outlet of the turbo-expander, intended for cooling an overheated low-boiling working fluid, and without a heat exchanger. Cycles in T–s coordinates were constructed for the studied schemes. The influence of pressure and temperature in the intermediate superheater on the exergetic efficiency of the turbo-expander unit was studied. Thus, the dependences of the exergetic efficiency and losses on the elements of the turbo-expander cycle are obtained when the temperature of the working fluid changes and pressure of the working fluid not changes in the intermediate superheater, and when the pressure changes and the temperature does not change. As a low-boiling working fluid, the ozone-safe freon R236EA is considered, which has a “dry” saturation line characteristic, zero ozone layer destruction potential, and a global warming potential equal to 1370. It has been determined that increasing the parameters of the low-boiling working fluid in front of the low-pressure turbo expander (regardless of the scheme of the turbo expander cycle) does not always cause an increase in the exergetic efficiency. Thus, overheating of the working fluid at a pressure exceeding the critical pressure causes a positive exergetic effect, but for each temperature there is an optimal pressure at which the efficiency will be maximum. At a pressure below the critical pressure, overheating leads to a decrease in the exergetic efficiency, and the maximum exergetic effect is achieved in the absence of a secondary steam superheater. All other things being equal, a turbo-expander cycle with a heat exchanger is more efficient than without it over the entire temperature range and pressure of the low-boiling working fluid under study.

INVESTIGATION OF EVAPORATION AND CONDENSATION PROCESS OF INDUCED FLOW USING STEAM EJECTOR

The research aims to understand the design parameters of steam ejector nozzle on the performance of flash evaporation induced by the effect of a steam jet passing through it. The research concentrates on studying the effect of ejector nozzle outlet diameter on induced flow from preheated water in a specified evaporator using a subsonic ejector. The thermal energy extracted from the condensed steam mixture in the condenser is used to heat the water in the evaporator. The experimental tests investigate the effect of nozzle geometry on the induced evaporation process by changing nozzle outlet diameter while keeping the pressure of evaporator, condenser and primary steam constant. The experimental results proved that both primary and secondary steam mass flow rates increase versus nozzle outlet diameter, while the entrainment ratio of secondary to primary steam flow rates decreases due to the restricted increase of the secondary steam mass flow rate. The mathematical model prepared to simulate the behaviour of the subsonic ejector is validated using the comparison between experimental and theoretical results. The mathematical model showed that maximum entrainment of 0.57 is obtained at a primary steam pressure of 2 bars when the nozzle outlet diameter is fixed at 1.5 mm, while minimum entrainment ratio of 0.17 is estimated at 1.5 bar pressure related to primary steam when the nozzle outlet diameter is fixed at 2.5mm. The authors recommend defining nozzle geometrical parameters according to the operating conditions of the experimental test rig to enhance ejector efficiency.

INTENSIFICATION OF CONCENTRATION SOLUTIONS TECHNOLOGIES IN THE FOOD INDUSTRY

The technological line for evaporating solutions in the food industry using a heat pump was optimized, which allowed the secondary steam to be diverted to the ejector, mixed with the primary one, resulting in an increase in the energy efficiency of the installation, and as a result, the consumption of primary steam was reduced. Various directions of improving the process of concentrating food solutions by evaporation are proposed, which can become the basis for the development of energy-saving technologies in this area.

Experimental Investigation of the Steam Ejector in a Single-Effect Thermal Vapor Compression Desalination System Driven by a Low-Temperature Heat Source

The paper presents an experimental investigation of a steam ejector in a single-effect thermal vapor compression (S-TVC) desalination system driven by a low-temperature (below 100 °C) heat source. To investigate the performance of the steam ejector in the S-TVC desalination system, an experimental steam ejector system was designed and built. The influences of the nozzle exit position (NXP), operating temperatures, and the area ratio of the ejector (AR) on the steam ejector performance were investigated at primary steam temperatures ranging from 40 °C to 70 °C, and at secondary steam temperatures ranging from 10 °C to 25 °C. The experimental results showed that the steam ejector can work well in the S-TVC desalination system driven by a low-temperature heat source below 100 °C. The steam ejector could achieve a higher coefficient of performance (COP) by decreasing the primary steam temperature, increasing the secondary steam temperature, and increasing the AR. The steam ejector could also be operated at a higher critical condensation temperature by increasing the primary steam temperature and secondary steam temperature, and decreasing the AR. This study will allow S-TVC desalination to compete with adsorption desalination (AD).

Assessment of RELAP/SCDAPSIM for Turbine Trip Transient in NuScale-SMR

The NuScale Small Modular Reactor (SMR) is an integrated Pressurized Water Reactor (iPWR) with the coolant flow based on the natural circulation. The reactor core consists of 37 fuel assemblies similar to those used in typical PWRs, but only half of their length to generate 160MW thermal power (50 MWe). Current study involves the development of a NuScale-SMR model based on its Design Certification Application (DCA) data (from NRC) using RELAP/SCDAPSIM. The turbine trip transient (TTT) was simulated and analysed. The objective was to assess this version of the code for natural circulation system modeling capabilities and also to verify the input model against the publicly available TTT results obtained using NRELAP5. This successful benchmark confirms the reliability of the thermal hydraulic model and allows authors to use it for further safety and severe accident analyses. The reactor core channels, pressurizer, riser and downcomer pipes as well as the secondary steam generator tubes and the containment were modeled with RELAP5 components. SCDAP core and control components were used for the fuel elements in the core. The final input deck achieved the steady state with the operating conditions comparable to those reported in the DCA. RELAP/SCDAPSIM predictions are found to be satisfactory and comparable to the reference study. It confirms the code code capabilities for natural circulation system transients.