Abstract The pressure to phase down high-global warming potential (GWP) refrigerants is increasing. This study compares the impact of three refrigerants R410A, R32 and R290 under high outdoor temperature (ODT) in range (30–50 °C) conditions utilizing a split-type air-conditioning system. The measurements were carried out in a calibrated test lab. The results show that exergy destruction increased by increasing (ODT). R410A demonstrated consistently large heat losses, especially in the compressor and condenser. R290 indicated the smallest absolute exergy destruction for most of the components. Generally, R290-based system is the lowest in terms of total exergy destruction by approximately 4–30% less than R410A. R290 shows also an increase in the total equivalent warming impact (TEWI) with the ODT from 30 °C to 50 °C about 35%, but indoor temperatures have small effect on this value about 5%. R32 decreases TEWI by about 20% compared to R410A while R290 is the lowest of about 30% with respect to R410A. These disparities are highlighting the importance of refrigerant selection in climate impact, especially in hot climates. It is concluded that R290 is showing potential as an environmentally friendly refrigerant.
Food-industry refrigeration must simultaneously reduce electricity use, replace high-global-warming-potential refrigerants, and make better use of rejected heat. This systematic review synthesises 101 peer-reviewed publications from 2015 to April 2026. Searches in Web of Science Core Collection, ScienceDirect, Scopus and IEEE Xplore identified 435 records; after deduplication, retrieval and full-text eligibility assessment, 101 publications were included and coded across four overlapping directions: heat recovery and useful heat valorisation (D1), energy efficiency and low global warming potential (GWP) refrigerants (D2), renewable energy sources (D3), and modelling, validation and control (D4). A structured descriptive appraisal considered study design, validation, uncertainty reporting, operating relevance and economic or environmental boundaries. The central research gap is the absence of integrated, experimentally validated studies, as these directions are still pursued largely in isolation rather than combined on a single installation. The urgent priority is therefore a comprehensive demonstration that unites refrigerant substitution, staged heat recovery, renewable-energy and storage integration, and dynamic monitoring and control on an operating food-industry installation, evaluated against a measured baseline across representative periods in each season using technical, energy, economic, environmental and operational indicators that capture the overall efficiency gain of the installation.
Abstract To reduce operating costs and prevent equipment damage through early fault detection in chillers, this study proposes an advanced diagnostic strategy integrating the Radial Basis Function (RBF) model with Exponentially Weighted Moving Average (EWMA) residual charts. While RBF models are proficient in handling nonlinear problems, they are often susceptible to overfitting and performance degradation under data disturbances. These limitations are overcome to optimize model parameters by the Differential Evolution (DE) and Genetic Algorithm (GA), achieving not only higher coefficient of determination coefficients (R2) but also low root mean square errors for two common types of nonlinear faults such as Refrigerant Leakage (RF) and Condenser Fouling (CF). Analysis using the ASHRAE RP-1043 dataset shows that the DE-RBF-EWMA model achieves a diagnostic confidence of 98.48% for the LMTDcd parameter and 98.56% for the Epsilon parameter. This strategy effectively identifies RF and CF across four severity levels, providing a robust tool for real-time chiller monitoring. The true alarm rate of the DE-RBF-EWMA model is the best, especially important at high serious level of faults, reaching 94.30% of RF and 74.90% of CF.
Abstract By showcasing OPTRs' ability to produce reliable cryogenic cooling with low vibration, the study draws attention to their potential for use in superconducting, infrared, and aerospace applications. To accurately depict steep temperature gradients, the model is solved using conservation equations, thermodynamic relations, and a flux-limiter approach. Furthermore, hybrid mesh regenerators (150–200-400 and 250–300-400 mesh combinations) are studied for performance optimization; they demonstrate significant advances in efficacy (up to 0.990) and decreases in pressure losses. An extensive analytical and numerical assessment of mass and energy conservation in inheritance-type Orifice Pulse Tube Cry coolers (OPTRs) is presented in this study. The objective is to create a proven mathematical model based on a one-dimensional control volume that incorporates compressible, oscillatory helium gas flow through essential components, including the pulse tube and regenerator.
Abstract This research presents a comprehensive exergetic and performance assessment of vapor compression refrigeration (VCR) systems integrated with a superheater, employing four refrigerants from different categories, namely R134a, R1234yf, CO₂, and R410a. All selected refrigerants possess zero ozone depletion potential (ODP). Among them, R1234yf and CO₂ are identified as low global warming potential (GWP) alternatives, while R134a and R410a represent conventional high-GWP refrigerants. The objective of this study is to evaluate the thermodynamic performance and environmental sustainability of the system through a detailed comparative analysis of these refrigerants. Exergy analysis, recognized as an effective tool for quantifying system inefficiencies and component-wise irreversibilities, is applied to the major elements of the refrigeration cycle, including the evaporator, condenser, expansion device, and compressor. Governing equations for exergetic efficiency and exergy destruction are formulated, and the system performance is examined under both superheated and non-superheated operating conditions. In addition, the influence of compressor isentropic efficiency is investigated over a wide range from 0.65 to 0.85 to assess its impact on overall system performance. The modeling and simulations are carried out using the commercial software Ecosim PROOSIS under varying operating conditions, with evaporator temperatures ranging from 248 to 298 K and condenser temperatures from 313 to 338 K. The results indicate that R134a achieves the highest exergetic efficiency among the refrigerants considered, followed closely by R1234yf, highlighting its strong potential as an environmentally benign replacement. An increase in both evaporator and condenser temperatures leads to a reduction in exergetic efficiency for all refrigerants, whereas a higher compressor isentropic efficiency significantly improves system performance. Furthermore, the incorporation of a superheater enhances the overall exergetic efficiency and reduces irreversibilities within the system. Overall, this study provides a valuable insights into combined effects of refrigerant selection, superheating, and compressor efficiency on the performance of VCR systems. The findings emphasize the feasibility of adopting low-GWP refrigerants, particularly R1234yf and CO₂, for developing energy-efficient and environmentally sustainable refrigeration technologies.
