Vol 112, No 2 (2023)

The root cause of refrigerant leaking from a household refrigerator’s compressor system can be traced to micro- and macro-damage within the sealed system. To determine and prevent further leakage, it is necessary to equip the refrigerator with an alarm device featuring a thermal balloon on the exterior of the freezer evaporator. This innovative device is designed to react solely to any drop in temperature across the surface of the freezer evaporator below its nominal value. For this purpose, the thermal energy indicators of a household refrigerator, considering variable ambient temperatures and the required refueling dose of the compressor system, were determined. This device does not replace an existing one; rather, it serves as a complement by interrupting the electrical circuit to the start-up relay; thereby, disconnecting the compressor from the power supply and alerting users to a potential refrigerant leak in the compressor system. This device can be implemented in compressor systems utilizing any type of refrigerant.

Distribution centers, ware houses, food processing plants — CO₂ applications in industrial scale are increasingly becoming the focus of operators, OEM’s and the refrigeration industry. Applications with 2 MW cooling capacity are no longer a rarity. Installations with the required capacity of up to 4 MW split between several systems with up to 65 compressors operate successfully. The convincing arguments in favour of the carbon dioxide installations are: lower safety requirements, less space for the machine room and good seasonal energy efficiency compared to installations with ammonia. Following the development of this trend BITZER designed compressors with eight cylinders for industrial applications. The main focus of the development was besides the usually high operational safety, efficiency, capacity regulation and a low oil carry over rate. This publication gives an overview of the system solutions applied in industrial scaled applications with carbon dioxide as refrigerant. Based on this, the paper describes the design of a new generation of compressors and its potential for industrial applications. It is not intended as a competitor to ammonia system solutions, but rather as an additional solution that is sustainable and based on a natural refrigerant.

BACKGROUND: Engineering support is crucial for controlling microclimate parameters in rooms experiencing high thermal excesses. It is necessary for mitigating the impact of technological processes on worker health. Recent instrumental research has classified the engine room of a high-voltage sewage pumping station as one such environment, owing to its specific technological conditions that result in significant heat generation. This has led to exploring the potential use of air conditioning systems for such type of rooms in buildings.

AIMS: The objectives are to assess the feasibility of implementing a central air conditioning system in the engine room of a city's high-voltage seweage pumping station and to calculate the capital costs for installing refrigeration elements.

MATERIALS AND METHODS: The study involved reviewing current scientific literature on the viability of air conditioning systems for such applications and conducting preliminary calculations of the required characteristics for refrigeration equipment. It was found that modern design solutions for refrigeration equipment can be integrated into the engine room.

RESULTS: The study found that installing an air conditioning system using an artificial cold source (refrigeration machines) for a structure operating with 5 pumps amounted to 49,450,000 rubles. For designs with 3 working units, the cost of the equipment was estimated at 25,650,000 rubles. Employing only air humidification strategies would reduce capital costs to 9,900,000 rubles (for 5 working pumps) and 5,800,000 rubles (with 3 working pumps).

CONCLUSIONS: Although implementing an air conditioning system in high-voltage sewage pumping stations is feasible, it requires large investments during the installation and operation processes. Operating costs during warmer months would be higher if only air humidifying equipment is used instead of installing refrigeration machines.

In this work, a novel CFD-database generation algorithm for CO₂ ejectors is presented. The algorithm is explained and its details discussed. A case for CFD database generation is then performed based on an ejector design for an industry client. The ejector design is investigated with different design parameters around the suggested design. Design improvements are suggested based on the numerical results, and a final design is suggested. The final design had a high ejector efficiency of simulated to be 46% at the design point, and the ejector performance is evaluated and discussed for off-design conditions.