This study addresses the limited condensation data for low-GWP R1234yf in staggered-fin plate heat exchangers (SFPHEs) for new-energy-vehicle thermal management. Condensation-side heat transfer coefficients and frictional pressure drops were measured using a modified Wilson plot method over mass flux G = 100–300 kg m⁻² s⁻¹, heat flux q = 12–18 kW m⁻², saturation temperature Tsat = 55–65°C (Psat ≈ 1.53–1.91 MPa), and mean vapor quality x̄ = (xin + xout)/2 covering 0–0.9. These ranges correspond to high-ambient NEV heat-pump and chiller condenser duty. Vapor-quality-dependent regime transitions govern performance: high x̄ sustains relatively high HTCs, intermittent flow causes the steepest decline, and at low x̄ the flow is liquid-dominated and intermittent but remains shear-dominated. Mass flux amplifies frictional losses; heat flux has a secondary effect; higher saturation temperature degrades HTC but lowers pressure drop. The fitted Nu and ff correlations describe 88.6% and 85.6% of the same data within ±20%. These percentages measure goodness of fit, not independent validation. The results provide guidance for sizing compact R1234yf SFPHE condensers.
Despite the fisheries sector contributing modestly to GDP in most Southern African Development Community (SADC) countries, it remains crucial for export earnings, food security, and regional trade integration. The main elements of this research investigate the determinants of total fisheries trade balance and trade intensity across 16 SADC countries using data from 2000 to 2022, employing static panel regressions and a Panel Autoregressive Distributed Lag (ARDL) model. The factors included in this analysis are total fisheries production, gross fixed capital formation (as a proxy for investment), exchange rates, GDP, GDP per capita, and trade openness. Results from static random-effects models show that total fisheries production has a positive effect on trade balance, while GDP per capita and trade openness significantly influence trade intensity. ARDL estimates point to the presence of major long-run macroeconomic factors influencing trade balance and trade intensity. At the same time, short-run factors affect GDP and GDP per capita. Exchange rates significantly affect trade intensity when they depreciate. Macroeconomic factors exert a stronger influence than production and investment factors. Policies should focus on maintaining stable macroeconomic environments, developing sector-specific infrastructure, including public ports and storage facilities, and privatizing processing or aquaculture facilities, as well as data reporting the enhance fisheries trade and regional integration.
The co-electrolysis of H2O-CO2 in solid oxide electrolysis cell (SOEC) enables stable production of H2 and CO, yet its large-scale implementation is hindered by low CO2-to-CO conversion rates and unresolved thermal--mechanical reliability issues in the electrode-electrolyte structure. Existing studies predominantly focus on optimizing CO2-to-CO conversion alone, overlooking the critical trade-off between conversion performance and thermal stability. To address this gap, this study develops a numerical model that couples electrochemical reactions, water gas shift (WGS) reactions, and thermal stress variations, and systematically evaluates the combined effects of operating and structural parameters on CO2-to-CO conversion and thermal stress. The results show that compared to counterflow, co-flow yields lower CO2-to-CO conversion but significantly reduces thermal stress in the electrode-electrolyte structure. Increasing temperature enhances CO2-to-CO conversion but aggravates electrolyte thermal stress, while 1023 K provides the most favorable balance between these factors within the investigated range. Elevating operating pressure has a more pronounced effect on reducing overall thermal stress than on improving conversion. In addition, using a porous conduit as the fuel gas path significantly increases the CO2-to-CO conversion rate while maintaining favorable electrical energy consumption and temperature distribution. Overall, this study provides a physics-based parametric assessment that integrates conversion efficiency and thermal stability and identifies favorable operating and structural conditions within the investigated range, offering useful guidance for the scale-up of SOEC-based co-electrolysis.
To improve protein structural stability during low-temperature spray drying and enhance the gel properties of rehydrated surimi gels, this study systematically evaluated the effects of maltodextrin, sucrose, pregelatinized cassava starch, lecithin, and ATP on the physicochemical properties of surimi powder and the quality of rehydrated gels. Compared with the control, ATP and sucrose increased solubility by approximately 41.99% and 36.15%, respectively. They also increased the absolute zeta potential by approximately 43.95% and 29.07%, respectively, while reducing surface hydrophobicity by approximately 70.76% and 52.42%, respectively (P < 0.05). After rehydration and heating, the storage modulus (G') at 90 degrees C increased by approximately 28% and 25% in the ATP and sucrose groups, respectively. Water-holding capacity (WHC) increased by approximately 28.27% and 21.79%, respectively. The proportion of immobilized water increased by approximately 8.82% and 7.62%, and gel strength increased by approximately 24.80% and 18.63%, respectively (P < 0.05). These changes contributed to the formation of a denser gel network, indicating enhanced intermolecular interactions and interfacial properties of surimi myofibrillar proteins. XRD, XPS, FTIR, SDS-PAGE, intrinsic fluorescence, and sulfhydryl/disulfide bond analyses showed that the protectants modulated protein conformation, molecular packing, and surface chemical composition. Combined with microstructural observations, these results indicated that ATP was the most effective protectant in alleviating protein denaturation and aggregation. Molecular docking further confirmed the stronger binding affinity of ATP for myosin and actin. Therefore, ATP showed greater application potential in this system and could serve as a novel protectant for improving the quality of low-temperature spray-dried surimi powder.
