To address the noise and vibration issues of high‑speed，large‑displacement scroll compressors，a dynamic model of the shaft system was established based on multibody dynamics theory.The force characteristics of the main and auxiliary bearings under high‑speed operating conditions were analyzed，followed by the optimized design of the motor counterweights.Subsequently，whole‑machine vibration tests were carried out for verification.The results indicate that，over the entire speed range of the scroll compressor，the loads on both the main and auxiliary bearings increase with the rise in rotational speed before and after optimization.After optimization，the bearing loads are significantly lower across the entire speed range.Specifically，at 8 000 r/min，the load on the main bearing is reduced by 21.06 N，and that on the auxiliary bearing by 7.73 N.Furthermore，over the full speed range，the optimized prototype exhibits lower vibration acceleration than the original prototype at most rotational speeds.At 6 000 r/min，the total vibration acceleration decreases from 20.41 m/s² to 9.88 m/s².This study provides theoretical support for improving the dynamic balance performance of high‑speed scroll compressors.

To improve the pressure retention and sand mixing effects of high‑energy mixing tanks，computational fluid dynamics methods and orthogonal experiment methods were used to analyze the influence patterns of different parameters on evaluation indicators such as inlet‑outlet pressure ratio，outlet particle volume fraction，and unit volume mixing energy of the mixing tank，determining the corresponding impacts of each parameter.The results show that the order of influence of outlet diameter，impeller rotational speed，sand inlet diameter，liquid inlet diameter，and number of blades on the three evaluation indicators （inlet‑outlet pressure ratio of mixing tank，outlet particle volume fraction，and unit volume mixing energy） exhibits differences.The influence of outlet diameter and impeller rotational speed on the inlet‑outlet pressure ratio shows a significant relationship at the 0.1 level；impeller rotational speed has a significant impact on unit volume mixing energy，with higher impeller rotational speed leading to greater unit volume mixing energy of the mixing tank；the optimal combination scheme to improve the sand mixing effect and pressure retention effect of the high‑energy mixing tank is：number of blades 4，liquid inlet diameter 203 mm，outlet diameter 240 mm，sand inlet diameter 365 mm，impeller rotational speed 800 r/min；the optimized mixing tank shows improvements in mixing time and energy consumption by approximately 12% and 22%，respectively.The relevant results can provide references for structural optimization and efficiency enhancement of similar high‑energy mixing tanks.

To address the issues of insufficient heat transfer capacity and operational instability during the operation of high‑pressure vaporizers，the core equipment of ship fuel gas supply systems，an anti‑icing ultra‑supercritical LNG high‑pressure vaporizer with a cold‑to‑hot plate distribution ratio of 1：3 was designed.A test facility for studying the heat transfer and flow performance of supercritical nitrogen-50% ethylene glycol water solution （50% EGW） was constructed.The effects of cold and hot side inlet flow rates on heat transfer and flow resistance characteristics were investigated，and the freezing risk during operation was dynamically assessed.The experimental results show that when the supercritical nitrogen inlet flow rate increased from 400 kg/h to 1 000 kg/h，the maximum temperature drop at the hot side outlet reached 5.93 ℃，while the average heat transfer capacity and overall heat transfer coefficient increased by 147.3% and 246.9%，respectively.Concurrently，the total pressure drop on the supercritical nitrogen side increased by 160 kPa （a 57% rise in friction factor）.In contrast，when the 50% EGW flow rate varied within the range of 10 669~17 071 kg/h，the heat transfer capacity remained stable，with the friction factor increasing by only 5.7%.When the hot side fluid of the high‑pressure vaporizer approached the freezing state，the heat transfer performance deteriorated significantly.This study reveals the heat transfer enhancement mechanisms and flow resistance evolution laws of high‑pressure vaporizers under supercritical conditions，providing a theoretical basis and data support for the structural optimization and anti‑icing design of high‑pressure vaporizers.

Aiming at the special flow and heat transfer characteristics of water‑based drilling fluid power‑law fluid，a combined method of experimental and numerical simulation was adopted to systematically study the flow and heat transfer behavior of power‑law fluid in serpentine channels.The experimental research was conducted within the Reynolds number （Re） range of 200~600，and the results show that the power‑law fluid still maintains high viscosity in this interval，with both convective heat transfer coefficient and pressure drop increasing with flow velocity，among which the maximum increase of convective heat transfer coefficient is 29.9%，and the maximum increase of pressure drop is 40.5%.The numerical simulation part covers the range of Re=240~2 900，when the Re value increases from 700 to 2 900，the Nusselt number （Nu） increases by 290.2%，while the pressure drop only increases by 109.9%.By comparing the flow and heat transfer characteristics of serpentine channels and straight channels，it is found that when Re≤700，the difference in Nu values between the two is small；when Re>700，the heat transfer performance improvement of serpentine channels is significantly higher than that of straight channels.In addition，the Nu value of power‑law fluid in plate structures gradually deviates from the calculated values based on empirical correlations for Newtonian fluids as the Re value increases，and is generally lower than the prediction results of traditional empirical formulas.The research can provide references for the optimal design of efficient and compact drilling fluid heat exchange devices on offshore drilling platforms.

Aiming at the special flow and heat transfer issues of drilling fluid power‑law fluid，experimental testing methods were used to study the flow and heat transfer characteristics of water‑based drilling fluid in helical tubes，where the Reynolds number of drilling fluid flow ranged from 727 to 6 810，and the heat flux density ranged from 4 849 to 14 546 W/m².The results show that the convective heat transfer coefficient and pressure drop of drilling fluid power‑law fluid both increase with Re，while the heating heat flux density has a small impact on the heat transfer coefficient and pressure drop；the obtained heat transfer Nu of drilling fluid power‑law fluid significantly deviates from the predicted values based on empirical correlations established for Newtonian fluids；the friction factor f aligns well with the predicted values of existing empirical correlations，with relative deviations within 18.11%；based on fitting experimental test data，an empirical correlation for heat transfer Nu of drilling fluid power‑law fluid was obtained，with relative deviations between predicted and experimental values less than 10%.The research results can provide references for the design of efficient and compact cooling heat exchange devices for drilling fluid power‑law fluid.

To address the design and operational optimization issues of falling film heat exchangers，high‑definition photography and digital image processing techniques were proposed to investigate the wettability of falling film flow outside multi‑row horizontal tubes.By constructing a ten‑row horizontal tube visualization experimental platform，liquid film distribution under three tube diameters，four tube spacings，and four inter‑tube flow patterns was analyzed.The “wetting length” indicator was proposed，and its variation patterns with tube diameter （d），tube spacing （s），and liquid film Reynolds number （Re_l） were analyzed.The results are as follows：increasing flow rate，tube diameter，and tube spacing all promote wetting length growth；when s/d=1.25，the optimal tube diameters for droplet，columnar，and sheet flow patterns are 16，25，25 mm，respectively；when Re_l≤505，the wettability ranking is l_{16 mm}>l_{19 mm}>l_{25 mm}，while when Re_l>505，it is l_{25 mm}>l_{16 mm}>l_{19 mm}.Correlation formulas for wetting ratio and total wetting length were fitted and compared with experimental values and literature experimental values，with average errors less than 10% and 8%，respectively，showing good agreement.The conclusion is that this can provide theoretical support for heat and mass transfer experiments and heat exchanger design.

Due to its advantages in enhanced heat transfer，the twisted oval tube heat exchanger has found certain applications in numerous industrial fields，including petroleum，chemical engineering，and electric power.Centering on its unique heat transfer and flow characteristics inside and outside the tubes，relevant researchers have carried out extensive studies.However，existing studies have failed to comprehensively elaborate on the mechanism of heat transfer enhancement，and there is a remarkable deficiency in summarizing its anti‑vibration performance.To address these gaps，this paper systematically reviews the research progress in the heat transfer and flow characteristics inside and outside the tubes of this heat exchanger，focuses on analyzing the key factors affecting its performance as well as the fluid‑induced vibration mechanism，and further summarizes and comments on the existing anti‑vibration methods and technologies.Results show that，by virtue of its unique advantages，this heat exchanger can achieve an actual energy‑saving effect of 20%~50% in its latest engineering applications，which provides theoretical support and practical reference for the in‑depth research and engineering optimization design of this new‑type heat exchanger.Finally，this paper puts forward the scientific and technical challenges that need to be solved in current research and presents an outlook on future research directions.

To address the issue of insufficient heat transfer efficiency in traditional heat sinks caused by increasing chip power density，a novel chip heat sink based on the synergistic effect of metal foam and porous ribs is proposed.Through numerical simulation，a 3D composite structure was constructed （using metal foam as the background area and porous ribs as discrete arrays in hotspot areas），with peak temperature，temperature difference，pressure drop，and equivalent thermal resistance as evaluation indicators，comparing the performance of the new heat sink with traditional metal foam heat sinks and porous rib heat sinks.The results show that under the conditions of coolant inlet flow velocity of 0.1~0.4 m/s and porosity of 0.8，the new heat sink has the lowest peak temperature （36 ℃，2 ℃ lower than the metal foam heat sink and 1 ℃ lower than the porous rib heat sink），the smallest temperature difference （3 ℃，1 ℃ and 4 ℃ lower than the former two respectively），and the lowest equivalent thermal resistance （1.3 K/W，7.1% and 10.3% lower than the former two respectively）；its pressure drop increase （300%） is lower than that of the porous rib heat sink （330%） and metal foam heat sink （302%），proving that the multi‑scale synergistic effect of metal foam and porous ribs can effectively improve heat dissipation performance.The research can provide references for the design of heat sinks for high‑power density chips.

To address the challenges of limited heat transfer performance，high simulation costs，and low optimization efficiency faced by the environmentally friendly refrigerant R290 （propane） with low GWP （global warming potential） and zero ODP （ozone depletion potential） in the design of efficient heat exchangers，a distributed parameter model and algorithm were established，significantly improving computational efficiency.The predicted heat exchange error was only 2.78%，showing good agreement with experiments.Selecting corrugation inclination angle （β），corrugation pitch‑to‑height ratio （p/b），and plate length‑to‑width ratio （L/W） as design variables，an artificial neural network （ANN） surrogate model was constructed and coupled with the non‑dominated sorting genetic algorithm II （NSGA-II） for multi‑objective parameter optimization.The results show that the model's mean squared error （MSE） is only 0.54%，and the coefficient of determination （R²） is as high as 0.996 6，demonstrating strong predictive capability.By comprehensively analyzing heat exchange performance and pressure drop cost and analyzing the Pareto front，the optimal parameter combination is obtained：β=50°，p/b=2.0，L/W=2.0，achieving a total heat exchange increase of 31.20%.The research results provide a reliable method for the efficient design of R290 plate evaporators，contributing to the performance upgrade and low‑carbon transition of environmentally friendly refrigeration systems.

To investigate the influence of geometric parameters on the thermal‑hydraulic performance of pillow‑plate heat exchangers （PPHE），numerical simulation method was used to systematically analyze the flow and heat transfer characteristics under different structural parameters.The structural configurations in existing research are relatively limited；therefore，taking pillow plates with equidistant weld spot arrangement S_T=2S_L=62 mm，h_i=6 mm，D_sp=10 mm as the reference condition，within the Reynolds number range Re=1 000~8 000，the effects of weld spot pattern and other geometric parameter variations on heat transfer performance were mainly investigated.The results show that as the transverse pitch S_T increases，both Nusselt number （Nu） and friction factor decrease；increasing the longitudinal pitch 2S_L causes the Nu to first increase then decrease，while the friction factor continuously rises；increasing the channel height h_i leads to a decrease in Nu but an increase in friction factor，thus causing the overall performance to decrease with increasing h_i；increasing the weld spot diameter D_sp enhances disturbance，resulting in improvements in Nu，friction factor，and overall performance.Under low Re conditions，the equidistant weld spot pattern （S_T=2S_L=62 mm） demonstrates better overall performance；while at high Re，the transverse weld spot pattern performs better than the equidistant and longitudinal patterns.In summary，reducing h_i，increasing D_sp，adopting equidistant weld spot arrangement at low Re，and using transverse weld spot arrangement at high Re can help improve the overall performance of pillow‑plate heat exchangers.The research results can provide theoretical basis for the structural design and performance optimization of PPHEs.