Longitudinal Tube Research Articles

Treatment of 52 Cases of Hypospadias by Longitudinal Section of Urethral Plate and Coiled Tube Urethroplasty

Objective: To investigate the indications and some problems in the treatment of hypospadias by longitudinal section of urethral plate and coiled tube urethroplasty. Methods: All the children were treated with longitudinal urethral plate section and coiled tube urethroplasty. Results: The penis of all the children showed the appearance after circumcision, with normal erectile function, urethral opening in the right position of the head of the penis, postoperative urethral fistula in 4 cases, urethral stenosis in 3 cases, ventral swollen penis in 5 cases, slight torsion of the penis in 2 cases, and slight downward curvature of the penis in 1 case. Discussion: For distal and middle types of hypospadias with low penile flexion and well-developed urethral plates, longitudinal section urethral plate incision urethral tube urethroplasty has good surgical effect, short operation time and fewer postoperative complications. It is a commonly used surgical method at present.

Design and simulation of a new type of fin-and-tube heat exchanger with trapezoidal slit fins

Slit fin-and-tube heat exchangers are extensively utilized in industry. The design of fin structure is crucial for improving the performance of heat exchanger and reducing energy losses. In this study, a new type of fin-and-tube heat exchanger with trapezoidal slit fins was proposed in this study. To determine the performance of the fins, physical and mathematical models of heat exchanger with the fin spacing Fp of 2.65 mm were established. The effects of structural parameters on heat exchanger performance were investigated by numerical simulation, which includes the slit height Sh, slit width Sw, transverse tube spacing Pt, and longitudinal tube spacing Pl. The effects of the four structural parameters on the comprehensive performance were analyzed by the evaluation index. The results revealed that the comprehensive performance of trapezoidal slit fins had increased by 9.6 % compared to flat fins. Furthermore, the influence degree of structural parameters on heat transfer performance was obtained based through the orthogonal experiments. The order of influence degree was as follows: Pl > Pt > Sh > Sw. Additionally, the optimal parameter combination was also obtained as follows: Sh = 1.47 mm, Pt = 42 mm, Pl = 27.5 mm, and Sw = 4 mm.

Heat transfer and fluid flow performance of an internally longitudinal finned tube: Numerical study and experimental validation

The characteristics of heat transfer and fluid flow of an internally longitudinal finned tube were numerically studied. The results were validated with published experimental data, comparing the heat transfer coefficient (h) and friction factor (f) calculated in our numerical study with the corresponding values obtained from experimental data, with a highest deviation of 6.3%. Exploring a novel hollow longitudinal fin design to enhance heat transfer and reduce pressure drop, while investigating key parameters like fin angle (θ), inscribed diameter (dins), and fin thickness (δ). Through comprehensive analysis, valuable insights are offered into optimizing thermal performance compared to traditional smooth tube configurations. The study reveals that a rise in Re leads to a rise in heat transfer coefficient and a reduction in friction factor. Notably, in the case of internally finned tubes at θ=30⁰,dins=10mm,andδ=0.5mm, the handf are 0.32−0.9and0.34−0.43 times higher, respectively, compared to smooth tubes under a constant mass flow rate ranging from 10kg/hto60kg/h. Furthermore, variations in dins impact the handf for internally finned tubes, with a decrease in dins resulting in increased handf. Specifically, at D/dins = 8, the handf exceed those of smooth tubes by 0.357−1.16and1.097−1.608 times, respectively, under a constant mass flow rate across the same range. Additionally, the study investigates the effects of δ on internally finned tubes, showing that as the δ increases, the handf increase. In the case of θ=30⁰,dins=10mm,andδ=2.5mm, the handf increase to 1.51−1.75and1.29−1.87 times higher, respectively, compared to smooth tubes under a constant mass flow rate from 10 kg/h to 60 kg/h.

Gain measurements of longitudinally excited CO2 laser using low-pressure gas without helium

The gain characteristics of a CO2 laser pumped by a longitudinal pulsed discharge were investigated to develop a compact He-free CO2 laser operating at a high repetition rate. The longitudinal discharge tube had an inner diameter of 0.8 cm and a length of 45 cm. High-voltage pulses with a discharge starting voltage of 13.4–30.2 kV at a rise time of about 321 ns were applied to the discharge tube. CO2/N2 mixture gas with mixing ratios of 1:0, 1:1, 1:2 and 1:3 was used. The small signal gain coefficient was measured by inputting a seed CO2 laser pulse into the longitudinal discharge tube. The small signal gain coefficient depended on the delay time between the start of the discharge in the longitudinal discharge tube and the input of a seed CO2 laser pulse, the gas mixing ratio, the gas pressure, the repetition rate and the input energy to the longitudinal discharge tube. In this work, in He-free gas, the maximum small signal gain coefficient at a repetition rate of 300 Hz was 2.11%/cm with a delay time of 30.4 μs, a CO2/N2 gas mixing ratio of 1:2, a gas pressure of 2.6 kPa and an input energy of 191 mJ.

Development of multi-module arranged in series using U-type longitudinal fin tube in thermal energy storage system

The performance of a thermal energy storage (TES) system for commercial applications can be improved using phase change materials (PCM). This study develops a vertical multi-module from a PCM for a TES system that achieves the same effect as a single-module by arranging multiple-modules in series as a U-type longitudinal fin tube to enhance the system's performance. The U-type longitudinal fin tube is designed to enhance heat transfer within the module, and a single-module is designed for multi-module applications. The TES system is analyzed to the average heat transfer rate, overall heat transfer coefficient, quantity of heat storage/release, and utilization ratio at different heat transfer fluid (HTF) flow rates, inlet and outlet temperatures and different number of modules. Consequently, the addition of several modules improves the thermal performance, and an increase in the HTF flow rate improves the average heat transfer rate. The overall heat transfer coefficient is used to analyze the thermal characteristics of the PCM. During the heat charging and discharging processes, the average heat transfer rates are 2.4 and 2.55 kW, respectively, and the quantities of heat storage and release are 5,153.59 and 4,771.79 kJ, respectively, for three modules. The overall heat transfer coefficient of the PCM exhibits similar results with an increasing HTF flow rate; it increases marginally from 42.25 to 45.8 and 9.9–10.8 W∙m−2∙K−1 as more modules are added. Further, the results of this study confirm that the relatively low HTF flow rates in the multi-module require the addition of several modules and that increasing the HTF flow rates limits the number of modules.

Comparing the results of testing a longitudinal tube weld by nondestructive methods

Defects of longitudinal tube welds identified by X-ray inspection are studied in order to determine possible causes of their occurrence and to assess the reliability of nondestructive testing results. Metallographic analysis shows that the base metal and weld metal meet the requirements of regulatory documents. The strength properties and the chemical composition conform to the standards. The contamination with non-metallic inclusions in the segregation streamers of the sheet extending to the edge and falling into the fusion zone was detected in X-ray photographs and incorrectly interpreted as a defect. This assumption is based on the correlation of X-ray patterns with the position of the grooves in the zones of the studied welded joints, but it ignores the results of studying by other nondestructive testing methods, and most importantly, it is not confirmed by metallographic studies. Neither were these defects found in the tubes during magnetic flaw detection by means of a UMD-101M device in the line of production of longitudinally electric-welded tubes. Erroneous defect identification during X-ray inspection happens in tube making. The results of the study show the expediency of the integrated application of different testing methods for a reliable assessment of the quality of tubes or pipes of both small and large diameters.

A novel fin efficiency concept to optimize solid state hydrogen storage reactor

The process of heat-driven mass transfer involved in hydrogen storage within metal hydrides (MHs) demands implementing a heat transfer system (HTS) to facilitate faster hydrogen charging and discharging. One effective method to enhance heat transfer is utilizing an HTS equipped with fins and a cooling tube. Among the crucial factors for optimizing the reactor, fin efficiency (FE) plays a vital role, although it has not been explored in unsteady processes like the present one. This study introduces a novel FE technique to optimize fins in a conventional longitudinal finned tube MH reactor based on LaNi5. Due to the intricacies of the problem, making analytical estimation of FE challenging, the authors turned to the concept of reverse engineering. This approach utilizes simulated data's temporal temperature profiles to calculate the FE. The number of fins is varied from 4 to 12 while keeping the total fin weight constant. Heat transfer performance improved as the number of fins increased, but the FE deteriorated from 0.89 to 0.56 due to the reduction in fin thickness. A performance index (PI) that considers the number of fins is introduced to assess the overall performance. Its values are 0.58, 0.79, 0.96, 1.05, and 1.1 for configurations with 4, 6, 8, 10, and 12 fins, respectively. The configuration with 8 fins is deemed optimal because further increasing the number of fins led to only marginal improvements in PI value. Subsequent optimization of fin shape, precisely radial tapering, had a minimal impact on heat transfer performance. Finally, the desorption behavior was examined for the optimal configuration with 8 fins of constant thickness.

Parametric analysis on thermal-hydraulic characteristics in variable-direction twisted-oval tube bundle in cross-flow

In this paper, numerical investigations on heat transfer and flow resistance characteristics of a variable-direction twisted-oval tube (VDTOT) were performed. The effects of different geometric parameters (transverse and longitudinal tube pitches, ratio of major to minor axis, twist angle and pitch) on the heat transfer coefficient, pressure drop and heat transfer capacity per pump work were investigated. Contribution ratios of different factors were also analyzed. The results show that the transverse tube pitch and twist angle have a great impact on the overall performance of the tube bundle. VDTOT realizes the synergistic enhancement of flow and heat transfer performance. Compared to the circular tubes, the heat transfer capacity of VDTOT bundles is increased by 13.6%–20.6 % under the same pump power consumption. The average deviations of Nu and Eu correlations fitted by the multiple regression method are 0.99 % and 1.64 %, which is helpful for the rapid design and optimization of VDTOTs.

An investigation on structural parameters optimization and coupled heat transfer of LNG submerged combustion vaporizer

Submerged combustion vaporizer (SCV) owns an extremely efficient multiphase heat exchanger adopted in the coastal liquefied natural gas (LNG) receiving terminal. Overall vaporization efficiency of SCV mostly depends on the matching relationship of structural parameters and coupled heat transfer characteristics, which has been rarely addressed in previous studies. In the present work, an integrated SCV experimental platform with handling capacity of 50 kg/h was set up to validate the reliability of numerical model and method. Additionally, on account of multi-parameter orthogonal combination optimization method, the effects and sensitivity orders of structural parameters (transverse tube pitch, longitudinal tube pitch, orifice size and number of distributor branch) on dynamics performance of SCV were investigated. Finally, the coupled heat transfer between gas–liquid two-phase flow and supercritical LNG gasification was revealed in view of optimized parameters. Results indicated that the transient numerical tube-side outlet temperature could be consistent with experimental data. For the shell-side heat transfer coefficient, the sensitivity order was transverse tube pitch > orifice size > longitudinal tube pitch > number of distributor branch. Nevertheless, for the shell-side pressure drop, the sensitivity order was longitudinal tube pitch > transverse tube pitch > orifice size > number of distributor branch. Under the condition of optimization scheme, the heat provided by gas–liquid two-phase flow could meet the requirements of supercritical LNG gasification, the NG outlet temperature might achieve approximately 272 K. The present outcomes could lay a foundation for the optimization design and deep understanding for actual SCV facility.

Scavenger receptor endocytosis controls apical membrane morphogenesis in the Drosophila airways.

The acquisition of distinct branch sizes and shapes is a central aspect in tubular organ morphogenesis and function. In the Drosophila airway tree, the interplay of apical extracellular matrix (ECM) components with the underlying membrane and cytoskeleton controls tube elongation, but the link between ECM composition with apical membrane morphogenesis and tube size regulation is elusive. Here, we characterized Emp (epithelial membrane protein), a Drosophila CD36 homolog belonging to the scavenger receptor class B protein family. emp mutant embryos fail to internalize the luminal chitin deacetylases Serp and Verm at the final stages of airway maturation and die at hatching with liquid filled airways. Emp localizes in apical epithelial membranes and shows cargo selectivity for LDLr-domain containing proteins. emp mutants also display over elongated tracheal tubes with increased levels of the apical proteins Crb, DE-cad, and phosphorylated Src (p-Src). We show that Emp associates with and organizes the βH-Spectrin cytoskeleton and is itself confined by apical F-actin bundles. Overexpression or loss of its cargo protein Serp lead to abnormal apical accumulations of Emp and perturbations in p-Src levels. We propose that during morphogenesis, Emp senses and responds to luminal cargo levels by initiating apical membrane endocytosis along the longitudinal tube axis and thereby restricts airway elongation.

Numerical Investigation on Heat Transfer and Flow Resistance Characteristics of Superheater in Hydrocracking Heat Recovery Steam Generator

The heat recovery steam generator (HRSG) was utilized to recover the waste heat resources of the catalyst’s regenerated gas with the objective to reduce the energy consumption of the hydrocracking process. In this study, the flow resistance and heat transfer performance of the superheater tube bundles in the hydrocracking HRSG were investigated via numerical simulation. The performance evaluation criterion (PEC1) was applied to characterize the comprehensive heat transfer performance of superheater tube bundles. The results showed that as the transverse tube pitch increased, the Nusselt number (Nu) showed a monotonically increasing trend, the Euler number (Eu) showed a monotonically decreasing trend, and PEC1 showed a monotonically increasing trend. As the longitudinal tube pitch increased, Nu exhibited a monotonically increasing trend, Eu showed a monotonically decreasing trend, and PEC1 showed a monotonically increasing trend. In the scope of the simulated results, as the transverse and longitudinal tube pitches were 110 mm and 95 mm, respectively, PEC1 reached the maximum value. Compared with the primary structural parameters, PEC1 increased by 2.32% and 8.50%, respectively. Finally, a new correlation was proposed to predict Nu and Eu of the superheater tube bundles in the hydrocracking HRSG.

Optimization of heat transfer performance of a micro‐bare‐tube heat exchanger using a genetic algorithm

AbstractThis study presents the optimization of the heat transfer coefficient of a micro bare tube heat exchanger. A physical and mathematical model of a micro bare tube heat exchanger was built in Matlab using the simplified ε‐number of transfer unit method. Using a temperature of minus 30°C and a 0.5–1.0 mm tube outer diameter, a 1.7–8.0 mm longitudinal tube pitch, a 1.7–5 mm transverse tube pitch, and a 1.0–5.0 m/s velocity at minimum free flow area, with carbon dioxide as the refrigerant, a comparative variation analysis was performed to optimize the heat transfer coefficient of a micro‐bare‐tube heat exchanger. The results demonstrate that the heat transfer coefficient increases as the inlet air velocity is increased from 1.0 to 5.0 m/s, with a final gain of 93.17%. The growth rate of the heat transfer coefficient steadily decreases with increasing inlet air velocity and gradually approaches zero. The effect of the gradual decrease of the tube outer diameter from 1.0 to 0.5 mm on the heat transfer coefficient is 22.52% greater than that of the gradual decrease of the transverse tube pitch from 2.2 to 1.7 mm. The study also carried out an optimization analysis on the distribution of four different variables in the heat exchanger. With the use of a genetic algorithm, the study found an optimal distribution to maximize the heat transfer coefficient. The following parameter values resulted in the maximum heat transfer coefficient: a maximum inlet air velocity of 5.0 m/s, a minimum tube outer diameter of 0.5 mm, a 1.7 mm longitudinal tube pitch, and a 1.7 mm transverse tube pitch.

Comparative Numerical Study of Melting Behavior of a Phase Change Material in Shell and Tube Latent Heat Energy Storage Unit With Longitudinal, Spiral, and Annular Fins in Horizontal and Vertical Orientations

Abstract Owing to the high storage capacity of the latent heat energy storage unit (LHSU), it is preferred among other types of thermal energy storage to overcome the mismatch between energy supply and demand. The orientation of the LHSU affects the melting process of the phase change material (PCM), and this effect could vary according to the fin shape of the LHSU. Thus, the present study aims to numerically examine the impact of vertical and horizontal orientations on the longitudinal, spiral, and annular finned shell and tube LHSUs. The computational fluid dynamics simulation solved the time-dependent conservation equations of mass, momentum, and energy in the three-dimensional domain. The enthalpy-porosity and the Boussinesq approximation were used respectively to simulate the PCM phase change and the change in density. The results show that the LHSUs have completely different behavior in the vertical orientation than in the horizontal orientation due to the various obstructions to the natural convection flow induced by the fins, depending on the fin shape, and the direction of natural convection flow. In the vertical orientation, the annular finned LHSU has a faster melting rate than the longitudinal finned LHSU by 25.6%. In contrast, in the horizontal orientation, the longitudinal finned LHSU melted more rapidly than the annular finned LHSU by 52.5%. The spiral finned LHSU performance was moderate between the two other finned LHSUs in both orientations due to its spiral shape that lies between the shape of the annular and longitudinal fins.

Flexible Needle Steering with Tethered and Untethered Actuation: Current States, Targeting Errors, Challenges and Opportunities

Accurate needle targeting is critical for many clinical procedures, such as transcutaneous biopsy or radiofrequency ablation of tumors. However, targeting errors may arise, limiting the widespread adoption of these procedures. Advances in flexible needle (FN) steering are emerging to mitigate these errors. This review summarizes the state-of-the-art developments of FNs and addresses possible targeting errors that can be overcome with steering actuation techniques. FN steering techniques can be classified as passive and active. Passive steering directly results from the needle-tissue interaction forces, whereas active steering requires additional forces to be applied at the needle tip, which enhances needle steerability. Therefore, the corresponding targeting errors of most passive FNs and active FNs are between 1 and 2mm, and less than 1mm, respectively. However, the diameters of active FNs range from 1.42 to 12mm, which is larger than the passive steering needle varying from 0.5 to 1.4mm. Therefore, the development of active FNs is an area of active research. These active FNs can be steered using tethered internal direct actuation or untethered external actuation. Examples of tethered internal direct actuation include tendon-driven, longitudinal segment transmission and concentric tube transmission. Tendon-driven FNs have various structures, and longitudinal segment transmission needles could be adapted to reduce tissue damage. Additionally, concentric tube needles have immediate advantages and clinical applications in natural orifice surgery. Magnetic actuation enables active FN steering with untethered external actuation and facilitates miniaturization. The challenges faced in the fabrication, sensing, and actuation methods of FN are analyzed. Finally, bio-inspired FNs may offer solutions to address the challenges faced in FN active steering mechanisms.

Longitudinal Seismic Analysis of Tunnels with Nonuniform Strata Considering the Effect of Karst

The longitudinal direction of shield tunnels is prone to seismic damage due to excessive deformation under seismic action, especially in nonuniform stratum. In this paper, the longitudinal dynamic response of the tunnel under different seismic effects is calculated based on the longitudinal equivalent stiffness model using the stratigraphic load model, and the seismic indexes such as longitudinal corner, tube sheet and joint bolt stresses are verified. The calculation results show that the longitudinal seismic weakness of the shield tunnel is in the interface between soft and hard strata and karst development. The longitudinal axial force of the structure is larger during the longitudinal excitation of seismic waves, and the maximum bending moment is mainly in the vertical plane, i.e., the vertical bending moment. The axial force of the tunnel is smaller during the transverse excitation of seismic waves. The maximum bending moment is mainly the bending moment in the horizontal plane, i.e., the transverse moment. The South Lake section of the Two Lakes Tunnel has good seismic performance in the event of a rare earthquake with a 50-year exceedance probability of 2%. The investigation can guide the seismic design of the South Lake section of the Two Lakes Tunnel.

Evolution of solar-type activity: acoustic and magnetic energy generation and propagation in $\beta $ Hydri (G2 IV)

We examine the acoustic and magnetic energy generation and propagation in beta Hydri (G2 IV). The underlying motivation for this work is based on the solar, stellar, and galactic relevance of beta Hydri (a star in the Southern hemisphere), which is readily understood as a prime example and proxy of the future Sun - thus allowing assessments and analyses of the secular decay of solar activity. Regarding the magnetic energy generation, we consider longitudinal flux tube waves. We also assess acoustic waves. For the acoustic wave energy flux, the difference between the results obtained for beta Hydri and the Sun is significantly smaller than typically attained for main-sequence stars, which is largely due to the gravity-dependence of the acoustic energy generation. Furthermore, we study the height-dependent behavior of the magnetic energy flux for different magnetic filling factors corresponding to different flux tube spreadings. Finally, we comment on possible directions of future research.

Parametric Study on Thermal-Hydraulic Characteristics of H-Type Finned Tube Heat Exchangers

In this paper, the thermal-hydraulic characteristics of H-type finned tube banks are numerically investigated on the basis of a more accurate and convenient calculation method of fin efficiency for H-type fins. Experiments are performed to validate the numerical simulations. The variations of the Nusselt number, Euler number, and comprehensive factor with the Reynolds number and seven geometric parameters of H-type finned tube banks are obtained. The results indicate that the Nusselt number is proportional to the Reynolds number, the slit width, the fin thickness, and the longitudinal tube pitch; but, it is inversely proportional to the tube row number, the fin height, and the spanwise tube pitch. As the Reynolds number, the tube row number, the slit width, the fin pitch, and the spanwise tube pitch increase, the Euler number decreases. The factor rises with the increase of the slit width, and there exists an optimal tube row number () at which the factor is the maximum. The correlations of the heat transfer (Nusselt number) and pressure drop (Euler number) of the 10-row H-type finned tube bank, which can nearly be considered to be fully developed, are presented. The numerical results and correlations have good applicability under different fluids and show good agreement with the experimental results and correlations.

Influence of fin configuration on the thermal performance of nanoparticle-enhanced latent heat storage system

Storing the thermal energy using the materials' latent heat capacity is a prominent and well-established technique; these materials are termed phase-change materials (PCMs). For low-temperature applications mostly organic PCMs are available. These PCMs possess very less thermal conductivity, which results in a low rate of heat transfer. To overcome this problem usage of fins and the addition of nanoparticles (NPs) to PCM are two potential methods. In the present study, three-dimensional numerical analysis of melting and solidification is performed on the radial, spiral, and longitudinal finned PCM-based shell and tube heat exchangers with the addition of NPs to PCM. Numerical analysis is carried out with various volume fractions of NPs in the PCM. Based on the study it is observed that the PCM-based heat exchanger with radial fins has the lowest melting time, average temperature, and energy storage ratio. For longitudinal fins melting time is maximum and it also has the maximum average temperature and energy storage ratio. It is observed that the addition of NPs showed a significant effect on the phase change process. For all the selected geometries the average exergy efficiency is not more than 4.4% during solidification.

Bio-inspired leaf-vein type fins for performance enhancement of metal hydride reactors

Hydrogenation of metals is an exothermic and reversible process. Thus, metal hydride reactors/devices become essentially heat-driven. Excellent heat control in the MH reactor is required to develop metal hydride devices such as H2 storage systems successfully. Few attempts at nature-inspired designs have proven to have good heat transfer capabilities. Based on this idea, the present study investigates novel bio-inspired leaf-vein type fins for the metal hydride reactor. Two reactor designs are proposed for heat transfer fluid flow, namely (i) central straight tube and (ii) narrow trapezoidal channels with 10 kg of LaNi5 as a sample alloy. Compared to longitudinal finned single tube reactors (LFSTR), these designs provided better heat transmission and temperature uniformity. For LFSTR, Case-1, and Case-2, 90% storage capacity was reached in 210, 145, and 80 s. Different fin configurations, such as parallel, inclined fins, and fins of different thicknesses, are investigated further in the design with narrow trapezoidal channels. The inclined fin configuration shows better performance, and it is further optimized by varying the inclination angle from 3 to 9° and the fin number from 2 to 4. The optimized design with a 7° inclination angle and four fins required 57 s to attain 90% storage capacity and reduced absorption time by 73% compared to LFSTR. The influence of operating parameters such as hydrogen supply pressure, inlet temperature, and velocity of the heat transfer fluid on the performance is evaluated for the optimized design.

Sensitivity analysis of structural parameters of a low-temperature heat pump sludge drying system

Optimizations of the heat exchanger of the heat pump drying system were usually carried out individually, linkage effect of the whole system in practical operating was usually not considered. In addition, for a heat pump sludge drying system, optimizations mainly concentrated on the operation parameters, few theoretical analyses focused on the effect of structural parameters to the system performance. In the present study, based on the laws of energy conservation and mass conservation, a steady-state model for the heat pump sludge drying system, which interconnects the refrigerant circulation and the moist air circulation, was established. Three variables which are coefficient of performance (COP), dehumidification rate (DR), and specific moisture extraction rate (SMER) are simultaneously introduced to evaluate the system’s operating and drying performances. Effects of the number of horizontal tube rows, the number of longitudinal tube rows, and the fin spacing to the above three variables are analyzed. The results show that the COP decreases with increasing the number of horizontal tube rows while increases with increasing the number of longitudinal tube rows and fin spacing. The DR increases with increasing the number of horizontal tube rows and fin spacing and decreases with increasing the number of longitudinal tube rows. The SMER has a similar variation trend to that of the DR due to their directly proportional relationship. Finally, based on the sensitivity analysis, the heat pump sludge drying system achieves better operating and drying performances when the fin spacing is 2.85 mm, the numbers of horizontal tube rows of the evaporator and condenser are 18 and 14, and the numbers of longitudinal tube rows are respectively 12 and 9.