STUDY OF CHANGES IN CURRANT DURING FAST FREEZING

Frozen berries have a number of undeniable advantages: they do not require additional preparation costs, are almost ready to eat, and most importantly, thanks to modern technologies, they retain almost twice as much nutrients as with other canning methods. Increasingly, there are risks associated with internal and external factors, as well as problems with excess yields that threaten not to sell the product fresh. short shelf life immediately after harvest, which increases the critical dependence on market prices. One of the progressive technological methods of processing fruit and berry products is quick freezing. The use of such freezing gives, first of all, a low degree of product damage, minimally reduces the biological value and taste characteristics, and the use of freezing does not significantly affect the quality of the thawed product.The main task of an industrial or commercial line for shock freezing of berries is to ensure almost instantaneous preservation of the product, which will retain all its nutritional value and taste. This is usually achieved by rapidly chilling the berries to -18 °C. By far the best option for extending the shelf life of freshly cooked food is to freeze it quickly. There are various options, but the best known is the freezing technology. For instant freezing without crystallization, it is necessary to provide a temperature of -5 ...- 18 °C. Experimental data were obtained during research. The temperature regime of storage of currants with the preservation of quality indicators using a freezing device is also considered. When frozen quickly, the berries should be blown from all sides or literally float in a stream of frosty air of the appropriate temperature. The duration of this process depends on the type and size of the berries, as well as on the intensity of the cooling air flow. The current direction in the field of research of frozen berries is the preservation of consumer properties of berries after freezing

Multidisciplinary Sensitivity Analysis of the Cooling System of a High-Pressure Turbine Blade in the Pre-Design Phase

The engine-cycle performance of jet engines can be improved by more efficient cooling systems, either by reducing the required cooling air or by intensifying the cooling efficiency with the same amount of cooling mass flow. However, the multitude of geometrical design parameters and the strong multidisciplinary aspect of cooling mass flow consumption optimization make designing the cooling systems extremely challenging. Integrating probabilistic methods into the thermal design process enables the automated evaluation of multiple design variants which contributes to the development of more efficient systems. In the present study, the sensitivity of a multi-pass cooling system to geometric variations is investigated. The cooling air flow, solved using a 1D, correlation based flow solver, is iteratively coupled with the 3D-FE thermo-mechanical analysis of the blade. The geometry of the cooling system is varied using the Harmonic-Spline-Deformation parametric, which has been extended to modify the wall thickness enabling to perform a geometrical-holistic analysis. Furthermore, the Elementary-Effects-Method (EEM) and the Monte-Carlo-Simulation (MCS) are compared to identify the most influential parameters and analyze their complex interactions. It is shown that the cooling system’s performance is mostly affected by the shape and position of the first web. Furthermore, MCS proves to be robust towards changes in design space while simultaneously enabling a more detailed analysis of the system behavior compared to EEM.

Performance Tests on a Novel Un-Finned Thermosyphon Heat Exchanger Requiring Single Charge

A novel design of an unfinned thermosyphon HPHX having a continuous closed tube loop which requires only a single charge is proposed for industrial waste heat recovery. The HPHX consists of 9×17 straight copper tubes in a staggered arrangement connected by 144 U bends. Without fins, not only are the pressure drops of the cooling air flow limited, but the cost, weight and maintenance effort can be greatly reduced. The thermal performance of this novel thermosyphon HPHX was tested with water at a filling ratio of 40%. The evaporator section is immersed in hot silicone oil, while the condenser section is cooled by air flow. The heat transfer rate (Q) reaches 6.65 kW at a heating pool temperature of 150 °C and a cooling air flow rate (F) of 1600 CMH, when the HPHX attains maximum effective thermal conductivity of 12,798 W/m-K. An ε-NTU theoretical model for single-tube thermosyphons was formulated with the boiling and film condensation modelled by empirical correlations. This model predicts the total resistance Rtot of the HPHX, which decreases with Q and F, with a total error of less than ±10%.

Hot gas ingestion in chute rim seal clearance of gas turbine

The Reynolds-averaged Navier–Stokes (RANS) solver was used to calculate, using a test rig to verify the accuracy. The interaction mechanism between different sealed cooling air and gas ingestion at the rotor-stator cavity and chute rim clearance has been investigated. Several groups of representative sealed cooling air flow were selected to explore the cooling efficiency, flow characteristics, tangential and radial velocity ratios in the cavity and the pressure potential field characteristics of trailing edge. The conclusions are obtained: the sealed cooling air flow rate has a significant marginal effect on the sealing effect. The gas ingestion behavior under the small sealed cooling air flow belongs to the disc cavity intrusion, and the intrusion and outflow regions at the of rim clearance are obviously divided into the intrusion characteristic section and the outflow characteristic section. The ingestion behavior under large sealed cooling air flow belongs to clearance ingestion, and the intrusion flow is limited to the chute rim clearance position, which cannot be further penetrated into the cavity. At this time, the clearance area and the cavity area become independent, and the gas ingestion characteristics depend more on the internal flow of the clearance and the vortex structure formed.

Thermal Characteristics Study of the Bump Foil Thrust Gas Bearing

In this paper, a thermo-hydrodynamic model of the bump foil thrust gas bearing is developed, which solves the coupled gas film three-dimensional energy equation, non-isothermal Reynolds equation, and the foil deformation equation. The effects of bearing speed, thrust load, and external cooling gas on the bearing temperature field are calculated and analyzed. The test rig of foil thrust gas bearing was built to measure the bearing temperature under different working conditions. Both simulation and experiment results show that there exist temperature gradients on the top foil both in the circumferential and radial directions. The simulation results also shows that the top foil side of the gas film has the highest temperature value in the entire lubrication field, and the position of highest temperature moves radially inward on the thrust plate side as the rotor speed increases. The gas film temperature increases with the increasing rotor speed and bearing static load, and rotor speed has greater effects on the temperature variation. Cooling air flow passing through the bump foil is also considered in the simulations, and the cooling efficiency decreases as the mass of gas flow increases.

Modelling of clinker cooler and evaluation of its performance in clinker cooling process for cement plants

Cement manufacturing requires cooling down of hot clinker at temperature of about 1350o C to temperature lower than 100 o C in a cooling system known as clinker cooler. Many plants are unable to cool the clinker below 250o C. This challenge led to scaling down of actual clinker cooler to a test rig size in the ratio 25:1 suitable for simulation. Computational Fluid Dynamics (CFD) tools (Solid-Works and ANSYS) were used to achieve the simulation. The clinker outlet temperatures obtained from simulations were validated with theoretical evaluation. Results showed that with clinker and cooling air flow rates of 0.2 kg/s and 0.54 kg/s respectively and with a clinker bed height of 0.6 m. An optimum cooler performance was achieved with clinker outlet temperature of 68 oC. The scaled down cooler was 15% higher than the existing cooler in terms of recoverable energy and 10% high in terms of energy efficiency. Keywords: Clinker Cooler, Computational Fluid Dynamics (CFD), Mass flow rate clinker and Mass flow air and Clinker Furnace.

Steady and Transient Thermal State of Turbine Disk Estimation for Life Time Monitoring

In connection with increasing intensification of the working process in a gas turbine engine and increasing requirements for economy, the problem of defining and monitoring the main parts lifetime is becoming more vital. Modern algorithms of the monitoring systems are based on taking into account the levels of part temperature and total equivalent stress throughout the flight cycle. Thermal and stress-strain states of the critical zones of the main parts are determined on the basis of information received from the sensors installed in the engine gas path. Turbine disks are located in the internal cavities of the engine and are cooled by air from the compressor. However, in some designs, the disk cavity can be separated from the place of cooling air bleed by several stages of non-contact labyrinth seals, which will lead to some delay in changing the parameters of the cooling air flow when changing the engine operating mode. It has been observed that if this situation is not taken into account, it can lead to significant errors (more than 40%) in determining the lifetime for the peripheral zone of the disk. At the same time, this error is minimal for the hub and the middle zone of the disk, and the existing monitoring algorithms can be used.

Thermal-Hydraulic Investigations of a Horizontal Dry Cask Simulator

Recent advances in horizontal cask designs for commercial spent nuclear fuel have significantly increased maximum thermal loading. This is due in part to greater efficiency in internal conduction pathways. Carefully measured data sets generated from testing of full-sized casks or smaller cask analogs are widely recognized as vital for validating thermal-hydraulic models of these storage cask designs. While several testing programs have been previously conducted, these earlier validation studies did not integrate all the physics or components important in a modern, horizontal dry cask system. The purpose of this investigation is to produce data sets that can be used to benchmark the codes and best practices presently used to calculate cladding temperatures and induced cooling air flows in modern, horizontal dry storage systems. The horizontal dry cask simulator (HDCS) has been designed to generate this benchmark data and complement the existing knowledge base. Transverse and axial temperature profiles along with induced-cooling air flow are measured using various backfills of gases for a wide range of decay powers and canister pressures. The data from the HDCS tests will be used to host a blind model validation effort.