Vol 113, No 4 (2024)

In compliance with the Russian Federation’s obligations under the Kigali Amendment to the Montreal Protocol—mandating a phasedown of hydrofluorocarbon consumption—the transition to natural refrigerants has become a strategic priority. This study quantitatively assesses the alignment between domestic production capacity of natural refrigerants—propane (R290) and propylene (R1270)—and actual/prospective demand in the transport refrigeration sector. Statistical analysis of data from 2020 to 2023 reveals that production capacity at JSC “NPP Sintez” fully satisfies R290 demand but falls short of R1270 requirements. Notably, even in this relatively low-refrigerant-intensity segment, a supply gap for certain natural alternatives is evident—highlighting the urgent need for scaling up domestic manufacturing infrastructure. The findings underscore that a successful HFC phase-down in Russia necessitates not only equipment redesign and retrofitting but also targeted industrial policy to expand high-purity natural refrigerant production. This case study provides empirical grounding for evidence-based planning of the national refrigeration sector’s decarbonization pathway.

Based on the results of literature analysis, the basic principles of designing a heat exchanger with heat pipes for use in air conditioning systems have been determined. The principle of operation and design of a heat pipe are described. A sequence of necessary steps for selecting the configuration of a heat exchanger with heat pipes is given, and a diagram for its step-by-step design is proposed. Recommendations are also given for selecting the working fluid, shell material, and wick design, and the differences between homogeneous and composite wicks are indicated. The limitations on heat transfer of heat pipes, the description, the reasons for these limitations, and formulas for calculation are given. An example of an installation using heat pipes as an exhaust air heat exchanger in a central air conditioner is given. A conclusion is made about the advantages of using heat pipes in air conditioning systems for heat recovery, indicating the reasons for the rare aplication of this type of heat exchanger. The result of the analysis of various methods for creating a heat exchanger with heat pipes are presented, taking into account the prospects for using heat pipes in air conditioning systems. It is noted that the rarely used design of heat recovery units in the form of heat pipes is interesting and very promising, although it has manufacturing complexities and requires qualified maintenance.

BACKGROUND: The global transition to low-carbon energy requires the development of efficient technologies for utilizing the cold energy of liquefied gases. However, existing solutions are expensive and have low efficiency. Gaps in the improvement of working fluids and Rankine cycle parameters limit the profitability of such systems. This study is aimed at selecting the optimal working fluid and operating conditions ensuring the least payback period and the highest energy efficiency.

AIM: To develop of a method for selecting the optimal working fluid and parameters of a closed Rankine cycle for regasification of cryogenic products, ensuring the highest energy efficiency and the least plant payback period.

METHODS: 1) Thermodynamic analysis, i.e. simulation of the Rankine cycle using the equations of energy, entropy, and exergy to estimate efficiency and energy losses;

2) Exergetic analysis to determine irreversible losses in system components (heat exchangers, turbine, and pump) and assess their influence on the overall efficiency;

3) Economic modeling to calculate the cost of equipment and operating costs based on empirical dependencies, followed by optimization based on the least payback period;

4) Multi-criteria optimization (Pareto method) to search for trade-off solutions between the plant capacity and capital costs for various working fluids;

5) Comparative analysis to assess the effectiveness of alternative working fluids (methane, oxygen, and organic refrigerants) based on thermodynamic and economic indicators.

RESULTS: The study allows to determine the optimal operating parameters of the system, including the choice of the working fluid, temperature conditions, and design features of heat exchangers, contributing to the development of more effective and profitable cryogenic power engineering solutions.

CONCLUSION: Methane used as a working fluid in a closed Rankine cycle provides the best performance in terms of power, efficiency, and payback. Further improvement of the system requires optimization of heat exchangers to reduce exergy losses.