Vol 114, No 2 (2025)

On February 5, 2025, the conference “Industrial and Commercial Refrigeration Market Today” was held as part of the business program of the “AirVent Moscow” exhibition, with the journal “Refrigeration Engineering” acting as a partner. This article summarizes the key outcomes of the event, which addressed the transformation of the refrigeration industry driven by international climate commitments, regulatory restrictions on hydrofluorocarbons (HFCs), and a critical shortage of qualified personnel. Emphasis is placed on the need for a holistic approach to refrigerant selection, urgent updates to educational curricula, and the integration of digital monitoring and control systems to ensure safety and energy efficiency. The article argues that sustainable industry development is only achievable through coordinated efforts among equipment manufacturers, designers, operators, regulators, and educational institutions.

This article examines the relevance of using ejectors in small- and medium-capacity natural gas liquefaction cycles, as they offer a lower-cost and more reliable alternative to turboexpanders. It is emphasized that the main difficulty in their design stems from the fact that traditional calculation methods, such as those of E. Ya. Sokolov and N. M. Singer, are not adapted for working with multicomponent, often two-phase (vapor-liquid) natural gas flows.

The study calculates the ejection coefficient using the method of E. Ya. Sokolov and N. M. Singer, as well as using the Caltec Surface Jet Pump Unit and Ejector Extension v3.0.2 software modules. The obtained calculated values are compared with experimental data obtained at an operating liquefaction plant in the village of Razvilka.

The analysis reveals significant discrepancies (from 28% to 69%) between all calculation models and actual results. Conclusions are drawn regarding the applicability of standard ejector calculation methods, and the main reasons for discrepancies with experimental data are identified. The primary cause of these discrepancies is identified as the lack of consideration of phase transitions (condensation) in the mixing chamber and the thermodynamic properties of the multicomponent mixture in the models. A conclusion is drawn regarding the need to develop a new, adapted calculation method.

BACKGROUND: One of the important tasks of modern industry is the improvement of heat exchangers (since practically no industry can do without this equipment). One of the most common heat exchangers is “pipe-in-pipe” type devices, which allow the processes of heating, cooling, condensation and crystallization of various working products. Regardless of the process being carried out, the improvement of heat exchangers should primarily be aimed at increasing the heat exchange capacity. One of the ways to increase it is to increase the surface area of heat transfer.

AIMS: A capacitive crystallizer of the “pipe in a pipe” type with ice freezing on the inner surface of the heat exchange pipe is considered as an object of research. A solution for improving the crystallizer is proposed, which allows increasing the heat exchange surface area by changing the profile of the heat exchange pipe.

MATERIALS AND METHODS: As a method of evaluating proposals for improving crystallizers, specific indicators obtained using computer modeling characterizing resource conservation in the manufacture of crystallizers and energy saving during their operation are used.

RESULTS: The crystallizers were evaluated according to the energy and mass efficiency of a typical design, a design with heat transfer intensifiers in the form of round rods fixed on the outer surface of the heat exchange tube and a design with a cross section of the heat exchange tube in the form of an epitrochoid with 8 lobes.

CONCLUSIONS: It is noted that both the presence of intensifier rods and the change in the profile of the heat exchanger tube of the crystallizer contributes to a uniform distribution of the coolant velocity in its inter-tube space. The uniformity of the distribution, in turn, will have a positive effect on the intensity of the ice freezing process. Also, both presented technical solutions improve the considered specific indicators of the energy and mass efficiency of the crystallizers.

BACKGROUND: This article presents the experience of 'Engineering Technological Solutions' in the field of reverse engineering of screw compressors based on the methodology of adaptive recalculation of rotor meshing. This approach allows designing rotor pairs compatible with existing compressor housings without compromising key performance characteristics. The results of the Howden WRVi compressor reengineering projects are presented. One of the factors confirming the recalculation accuracy is the compressor flow coefficient, which shows a minimal deviation from the original values.

AIM: to evaluate the possibility of reengineering screw rotor pairs using adaptive recalculation methods.

METHODS: The lack of original spare parts compromises the reliability of equipment and forces companies to seek import substitution solutions. The article describes an adaptive recalculation methodology that takes into account not only the geometry of the original rotors, but also a number of operational factors. Examples of successful compressor reengineering projects are given, and the validity of the solutions is confirmed by analysis and comparison of flow coefficients.

RESULTS: Engineers at 'Engineering Technological Solutions' have developed design documentation for screw rotors. The components were calculated using an adaptive recalculation methodology. Currently, these rotor pairs are in the industrial production stage. The application of the proposed method for recalculating the geometry of screw rotors led to a change in their profile. At the same time, the key operational characteristics of the compressors were maintained at the initial level. Analysis of the flow coefficient λ shows that the new calculated value has minimal deviations of more than 2% from the initial parameter, which further confirms the accuracy of the calculations.

CONCLUSIONS: The studies conducted confirmed the feasibility of re-engineering screw rotor pairs using the adaptive recalculation methodology. The minimal deviations in the flow coefficient indicate that the modernised rotors maintain the operating parameters of the compressors at the level of the original units. The redesign of the rotor structure ensured the technological feasibility of manufacturing rotor pairs using existing Russian production capacities, which makes the proposed approach an effective tool for import substitution.