Vol 114, No 3 (2025)

In mid-June 2025, Maxim Sergeevich Talyzin, Editor-in-Chief of the journal “Refrigeration Engineering” and PhD in Engineering, attended the 15th International Exhibition “Rosplast 2025,” dedicated to equipment and materials for plastic products manufacturing. Following the event, this article was prepared to address the economic rationale for conducting technical audits of cooling systems at enterprises employing injection molding. The study analyzes the critical role of chillers as a core component of the production cycle, quantifies the financial impact of their failure, and demonstrates the cost-effectiveness of preventive maintenance. Findings indicate that scheduled audits can prevent up to 90% of unplanned downtimes, reduce scrap rates, enhance energy efficiency, and extend equipment service life by 3–5 years. The economic assessment clearly shows that expenditures on cooling system maintenance yield substantial returns by avoiding potential losses that may reach several million rubles per day.

BACKGROUND: Microwave disinfestation technique is potentially very suitable for postharvest treatment to control pests on food crops.

AIM: The purpose of this work is to study the process of disinfection of chickpeas using microwave technology and to assess its effect on nutritional value, microbiological parameters and thermophysical properties of the product.

METHODS: The samples of chickpea supplied from the ware houses of Pyin Oo Lwin were used for disinfestation. Physicochemical composition (nutritional value) of representative samples was also determined before and after treatment at Food Nutrition Analysis Laboratory. Furthermore, calculating the thermo-physical properties (specific heat) was performed to achieve a good thermal effect on food product. The samples were exposed with microwave energy levels 3 kW in different times of 60 s, and 80 s at 80 °C. The optimized as well as suitable exposure time of 80 s was chosen for the storage period, 12 months. The microbial population (yeast and mould) in food product was also determined during storage intervals.

RESULTS: Calculating equation for mass product production was developed dependent on heat transfer equation to know the definitely volume (mass) of food product. The amount of volume (mass) of chickpea required for experimental research was calculated. From these observed results, it was found that physicochemical composition of control and treated samples occurred no significantly changes due to microwave radiation effect on the samples. Initial total fungal count of chickpea is 2.0 × 10³ cfu/g, after 12 months: control — 70, treated 60 s —10, treated 80 s — 4 × 10³ cfu/g.

CONCLUSION: It was found that the application of microwave energy levels 3kW in 80 second at 80 °C would improve the hygienic quality and extend shelf-life of food (chickpea) sample.

BACKGROUND: Conventional evaluation of refrigeration system performance based solely on the coefficient of performance (COP) fails to identify localized irreversible losses, particularly those arising from pressure drops in heat exchangers. This limitation is critical in applications demanding high temperature stability, such as pharmaceutical refrigeration.

AIM: To perform a comparative thermodynamic analysis of a single-stage vapor-compression cycle using refrigerants R134a, R410A, R507A, and R717, explicitly accounting for the effect of condenser pressure drop on entropy production distribution across cycle components.

METHODS: The entropic and statistical method of thermodynamic analysis (ESMA) was applied. Simulations were conducted at a fixed cooling capacity of 1 kW, evaporation temperature of –10 °C, and condensation temperature of +42 °C. Condenser pressure drop was varied from 0 to 2 bar in 0.2-bar increments.

RESULTS: Increasing the pressure drop to 2 bar reduced thermodynamic efficiency by 8–13%, depending on the refrigerant. R410A demonstrated the highest resilience: its COP decreased by only 8%, and additional power required to compensate for entropy generation amounted to 3.8% of total compression power.

CONCLUSION: The entropic and statistical method of analysis (ESMA) allows for losses in different refrigeration plant components to be calculated and compared to determine the elements that need measures to increase their operation efficiency.

The relevance of this study stems from the need to ensure uninterrupted, safe, and cost-effective operation of refrigeration equipment in food industry enterprises, where temperature control is critical for product quality and regulatory compliance. Under a single-shift operational model, even temporary absence of qualified personnel may result in severe operational and financial losses. This article presents a techno-economic justification for implementing an internal training course on refrigeration system operation and maintenance. A comparative analysis of two strategies — direct hiring with in-house training versus outsourcing maintenance functions — is conducted. Although outsourcing demonstrates lower direct costs, staff training significantly reduces operational risks, shortens new employee onboarding periods, improves personnel retention, and increases equipment technical availability. Economic analysis revealed a positive return on investment (ROI ≈ 43.7%) and a payback period of 1.4 years.