Inlet Pipe Research Articles

Rancang Bangun Alat Pengasap Tipe Paralel

This research aims to design, manufacture and test a parallel type smoker which has an output that can be controlled and has uniform temperature in each smoker cabinet. In this research, design, assembly, testing and temperature regulation were carried out. This parallel type smoker has 3 main parts, namely the combustion stove, inlet pipe, and smoking cupboard. In the inlet pipe there is a faucet which functions as a control for the smoke output and temperature from the combustion stove to the smoking cupboard. In terms of testing, this tool was tested in several stages, namely trial 1, trial 2, and performance test. After the test is complete, the final stage is carried out, namely equalizing the temperature in each cupboard. The trial phase 1 was carried out with treatment on the operation of the smoke cupboard. Where the stages of operation of all cupboards are carried out simultaneously, then operation of 2 cupboards is carried out and one path is closed alternately. The results showed that the tool experienced problems in the form of unstable temperatures and leaks in the smoker cupboard, so it required patching with silicon. After design improvements have been made, trial 2 and performance testing are continued. Trial 2 was carried out to find out whether the tool still had problems or not before carrying out a performance test. The treatment for trial 2 was the same as that given during trial 1. As a result, the device had no leaks and the temperature was stable and the device was ready to operate at the 15th minute. After that, a performance test was carried out which had the same stages as trials 1 and 2. This is intended to see whether the tool is in accordance with the results during testing or not. After the performance test is carried out, the final stage is to equalize the temperature in each cupboard to produce the same and stable temperature. This equalization is done by adjusting the opening of the faucet valve on the inlet pipe. The results obtained were a parallel type smoker which had 3 smoking cabinets with the same temperature around 37oC. This temperature can used for low smoking temperature.Keywords: Design of Smoker, Parallel, Temperature.

The Effect of a New Approach to Cooling the External Heat Exchange Surfaces of a Car Cooler with Air Nozzles on the Cooling Process

The paper deals with an experimental investigation of a new approach for cooling the external heat exchange surfaces of a cooler using an air pressure nozzle system. The G12+ coolant (50:50 ethylene glycol/water concentrate) is heated to an operating temperature of 80 °C and cooled by a cooler. Three ways of forced cooling of the external heat exchange surfaces of the cooler are experimentally compared—fan, nozzles, and a combination of nozzles and fan. The spacing between the nozzles and the cooler is variable from 60 to 170 mm in inline and staggered nozzle arrangements. Coolant temperatures in the cooler inlet and outlet pipes are recorded by thermistors. The air pressure nozzle system achieved an improvement in the cooling process compared to a conventional fan. At a spacing of 160 mm, the heat exchange surface is completely covered by the air flow, which leads to a reduction in cooling time and an increase in the temperature difference. The maximum temperature difference of 28.84 °C and 16.90 °C for staggered arrangement of nozzles at a spacing of 160 mm are achieved for the combination of nozzles with fan and nozzles, respectively. When comparing 60 mm and 160 mm spacing, there was an increase in thermal performance of 70.3%, 55.99%, 6.20%, and 1.83% for inline nozzles, staggered nozzles, fan with inline nozzles, and fan with staggered nozzles, respectively. The air nozzle system fully replaces the fan in the cooling process and achieves improved heat dissipation, making the cooling process significantly shorter and more efficient. In addition, the air nozzle system can also be used as an additional equipment for intensification of heat dissipation in combination with the fan.

Analysis of the Possibility of Modeling Gas Separators using Computational Fluid Dynamics

Abstract Today, gas-liquid separators are usually used for the purification of gas mixtures from droplet liquid, and there are many designs of which. However, in order to improve the efficiency of their work, increase throughput, reduce mass and dimensions, they are constantly being improved. Usually, developing a new or improving an existing separator design is a long-term and relatively expensive process. Today, computer programs that implement the finite element method make it possible to speed up and reduce the cost of designing both a gas separator and other equipment. FloEFD program is one of these programs. However, it is more convenient during design to use one computer program that allows you to build 3D models (CAD) and in the same program to use a module for simulating the movement of gas and liquid flows (CFD). Such a program is SolidWorks with the FlowSimulation application module. As for the physical processes that occur during the operation of gas separators, they are quite complex, since a multiphase gas flow with an existing liquid phase is simulated. In the article, simulation modeling of the C-2-1 separator was carried out and the values and distributions of velocities and pressures in its various cross-sections were determined. Special attention was paid to the following cross-sections of the separator: along the axis of its inlet pipe; in the middle is the spigot of the blade screw; on a block of blinds. The difference in pressure at the outlet and inlet of the separator was determined, which is 20267 Pa. Based on the simulation results obtained, recommendations are given for further research and optimization of the separator design. The main parameter that characterizes the degree of separation of liquid from gas in the separator is the efficiency factor, which depends on the design of the separator, thermobaric conditions, parameters of the technological scheme, composition and physical and chemical properties of the gas-liquid flow. As a result of simulated modeling of the separator, its efficiency coefficient was determined when it extracted droplet liquid from the gas-liquid mixture in its various fractions (from 0.01 to 0.1 mm). The efficiency factor is about 100%.

Role of flow structures on the deposition of low-inertia particles in turbulent pipe flow

We analyze the effect of large-scale coherent structures on the deposition of low-inertia particles in a turbulent pipe flow using extended proper orthogonal decomposition (EPOD) and spectral analysis. We perform direct numerical simulations (DNSs) at two the Reynolds numbers 5300 and 10 300 (based on bulk parameters) with the particles released at the pipe inlet. The equilibrium Eulerian model is employed for calculating particle velocity, and the analysis is limited to particles with Stokes number (based on wall units) less than 1. Increasing the Stokes number increases the energy at small streamwise wavelengths (due to inertial clustering), and the spectral energy peak moves from λz+≈1000 to λz+≈150. The spectral peak in the (λz+,y+) plane, where y+ is the wall-normal distance, moves from the buffer layer to the logarithmic region. Gravity has a substantial effect on the POD mode shapes. For the downward flow, a second peak appears closer to the center. A new Fukagata-Iwamoto-Kasagi (FIK) identity is derived for the wall deposition rate coefficient (Sherwood number, Sh) and employed to quantify the contributions of the mean and fluctuating velocity and particle concentration fields for different Stokes, Froude, and Reynolds numbers. Modes with azimuthal wave numbers kθ equal to three or four are found to contribute most to deposition. Application of the developed methodology to higher Reynolds number can elucidate the role of large- and very-large-scale flow structures on particle deposition to the wall. It is well known these structures leave their footprint at the wall but their contribution to deposition is not well understood. Published by the American Physical Society 2024

Experimental study on leakage characteristics of gas-liquid two-phase flow in a horizontal pipe

Oil and gas pipeline leakage accidents caused by aging and third-party damage have increased, resulting in polluting the ecological environment and jeopardizing life and property safety. A detailed and systematic investigation on the leak characteristics of oil and gas two-phase pipelines is significantly urgent. The leak experiments were performed on a horizontal tube with a diameter of 32 mm. There was a 3 mm round leakage hole at the bottom of the tube. The distance of the leakage hole from the pipe inlet was 4.8 m. Three inlet flow patterns, including stratified flow, slug flow, and annular flow via adjusting the gas superficial velocity (1.73 m/s ≤ USG ≤ 24.19 m/s) and liquid superficial velocity (0.017 m/s ≤ USL ≤ 0.415 m/s), were obtained. The conclusions point out that the type of leakage, whether it is mainly liquid or both gas and liquid, depends on the USG. The degree of phase separation in stratified flow is the greatest among the three inlet flow patterns, with a maximal phase separation efficiency (η) of 0.403. Slug flow has the least phase separation degree. Interestingly, the η is directly proportional to the inlet mass fraction only for slug flow. The harmonic frequency that appeared in the power spectral density curves for the pressure difference of leakage hole in slug flow, indicates that leakage is not a standard periodic event. The liquid velocity loss is primarily related to the gas leakage mechanism. These findings can provide new insights into two-phase pipeline leak detection and accident consequence prediction.

Surging parametrization for gas-liquid centrifugal pumps

The present work investigates the dimensional and similarity representations of two-phase flows in centrifugal pumps. A new parametrization scheme is advanced for the capacity (ϕ=Q/ωD3) and head (ψ=gH/ω2D2) coefficients in terms of the non-dimensional parameters β (no-slip volume gas fraction) and Ω (= ωD/UM, UM = mixture velocity in the inlet pipe). The new parametrization yields universal performance curves that capture the positions of performance degradation (ϕcr and ψmax) and the appearance of surging. The new expressions are supported by a comprehensive set of experiments carried out for volume gas fractions up to 12% and four rotational speeds. The experimental conditions cover the four different flow patterns commonly described in the literature. The experiments are conducted with water and air. The flow parameters are characterized through global parameters (pressures, flow rates). The work confirms the rotation speed as a relevant parameter in the performance determination of gas–liquid systems and shows its relation to bubble breakup and the definition of the four observed flow patterns. The particularly introduced parametrization equations are limited to the geometry of the pump that is tested. The developed methodology, however, is expected to be extendable to pumps of different geometries.

Performance of a low-cost hydraulic ram pump as a function of variations in feed height and inlet pipe diameter

Access to water in rural areas is extremely important in the different activities that occur daily on agricultural properties, whether for human consumption, animal watering, irrigation and other purposes. This access is often difficult and costly, especially for small rural producers who do not have the financial capacity to purchase an electric pump, or do not have electricity on their property. In this sense, alternative water pumping, without the need to use electrical energy or energy from the burning of fossil fuels, can be a good alternative and deserves to be studied. Based on these premises, the objective of this research was to study the performance of the repressed flow, obtained by a low-cost hydraulic ram, installed in different hydraulic scenarios. The methodology consisted of installing equipment built in the Irrigation, Hydraulic and Hydrology Laboratory of the Agricultural Sciences Center of the State University of the Tocantina Region of Maranhão (LIHH/CCA/UEMASUL), for this, different hydraulic scenarios were created depending on the interaction of different feeding heights and different pipe diameters, which constituted the experimental treatments. The results found allowed us to conclude that the highest average pressure flow was obtained in the hydraulic scenario that presented the greatest geometric difference between the water source and the hydraulic ram with the largest diameter of the inlet pipe, with an average of 9,539.21 L.d-1 of repressed water. It was also possible to prove that this equipment constitutes a good alternative for pumping water on small rural properties.

Exploring the air impacts on the state development of pipe flow using the smooth particle hydrodynamic method

Abstract It is widely recognized that the water flow in pipes can be affected by trapped air pockets. However, the underlying air–water interactions of free flow with non-jacking downstream of the pipe are rarely investigated. There are no studies at this time that clearly elucidate the differences in pipe flow between the vacuum and the presence of air in the free flow case. To this end, the smoothed particle hydrodynamics (SPH) method is applied to study the air–water hydraulic dynamics in the pipe under free flow. We perform SPH simulations in several different scenarios and find that (i) the SPH method is competent to simulate both single- and two-phase flows in the pipe due to its outstanding advantages in capturing complex interfaces; (ii) only when the upstream water level is higher than the top of the pipe inlet, and the water level in the pipe rises to the top of the pipe due to air resistance, can a full pipe flow be formed; and (iii) the presence of air can cause the water to form a full pipe flow, causing a siphon-like effect that promotes pipe drainage. These results provide insights into the underlying complex air–water hydraulic properties in pipe flows.

Effect of reduced diameter pipeline and impeller position on the performance of reactor coolant pump

In the reactor coolant pump experiments, there are cases where different impellers are replaced on the same volute for experiments, but due to the different diameter of the impeller inlet, there will be a sudden expansion between the inlet pipeline and the impeller inlet, resulting in a decrease in the efficiency of the pump. In order to solve this problem, a scheme of using an inlet pipe with a reduced diameter structure and changing the position of the impeller was proposed, and based on the three-dimensional incompressible Reynolds N-S equation, the reactor coolant pump device was numerically simulated by CFD software. The data simulation results of the reduced diameter structure, straight pipe flow field and changing the position of the impeller were compared with the model experiments, and the reliability of the calculation results was verified. The results show that the inlet pipe with reduced diameter structure and the method of changing the position of the impeller can effectively solve the problem of efficiency decline caused by the sudden expansion of the flow channel.

Numerical simulation of the flow field inside mixer

When transporting oil in the petroleum industry, due to its high viscosity, cooling can have an impact on the transportation process. It is usually necessary to use a mixer to mix it with cold and hot to increase the temperature of the oil during transportation. In order to study the influence of the inlet pipe diameter of the mixer on mixing efficiency, internal flow field, and temperature field, the temperature distribution and velocity vector in the horizontal and wall directions of the mixer under different pipe diameters are simulated and analyzed using Fluent software in this paper, and pressure and temperature curves are drawn. The following conclusion was drawn: increasing the inlet diameter can not only alleviate the vortex phenomenon caused by the high inlet speed inside the mixer, but also reduce energy loss during water mixing and control the phenomenon of uneven velocity distribution inside the fluid.

Experimental research on similarity deviation between prototype and model pumping systems

To investigate the reasons for the flowrate deviation of the prototype pumping systems between the measured value onsite and the calculated one by the similarity law, the energy characteristic relationship of the prototype and model pumping systems under different working conditions was compared and analyzed. It was pointed out that the hydraulic loss in the outlet passages caused by the residual velocity circulation is not similar. Using the method of vessel-mounted ADCP and water level gauges to measure the flowrates and heads of pumping stations, the energy characteristics of three typical pumping stations were obtained, and the comparisons with the characteristic curves of the pumping systems predicted by similarity law are made. It was found that there was a deviation between the two in most cases, and the similarity deviation of the elbow inlet and siphon outlet passages was greater than that of the straight pipe inlet and outlet passages. Meanwhile that the larger the blade angle (or the higher the rotational speed of pump), the greater the similarity deviation. Therefore, in the design of the pumping system, the energy characteristics of the model pumping system cannot be simply converted by the similarity law to predict the characteristics of the prototype pumping system, but the influence of different factors on the similarity deviation between the prototype and model pumping system should be considered carefully.

Analytical solution for laminar entrance flow in circular pipes

This study introduces an analytical solution for the laminar entrance flow in circular pipes, aiming to confirm the occurrence of velocity overshoot. Velocity overshoot is characterised by the maximum axial velocity appearing near the pipe wall instead of the central axis. Similar to the previous studies, the analytical solution is derived from the parabolised Navier–Stokes equation; however, the specific approach used in linearising the momentum equation has not been attempted before. The accuracy of this analytical solution has been verified through a comprehensive comparison with various published experimental data. The existence of velocity overshoot at a short distance from the inlet, which is evident in numerous numerical calculations based on the full Navier–Stokes equations and corroborated by recent magnetic resonance (MR) velocimetry experiments, is identified analytically for the first time. The parabolised Navier–Stokes equation has inherent self-similarity with respect to the Reynolds number, implying that $Re$ is incorporated into the dimensionless variables rather than serving as an independent flow parameter. According to both MR velocimetry measurements and the present analytical solution, the self-similarity is not valid immediately following the pipe inlet, and this becomes more evident as $Re$ decreases; hence, the analytical solution derived from the parabolised Navier–Stokes equation cannot accurately predict the evolution of the velocity profile within this region near the pipe inlet.

Аналіз конструкцій глушників вакуумних насосів

The substantiation of the structural and functional scheme of the muffler filter of the rotary vane vacuum pump, which has the ability to separate oil from air and collect it for further processing, has been completed. The proposed design, due to its design feature, provides sound suppression, reduces noise and has minimal resistance to the movement of the air flow in the middle of the muffler filter. The muffler filter is based on the fact that air, together with the oil that lubricates the vacuum pump nodes, enters the muffler filter through the inlet pipe at a speed of 11...16 m/s, which allows the most complete separation of oil from air. The trajectory of the movement of air in the muffler is described by a helical winding, and therefore, centrifugal force acts on the oil particles in a suspended state, as a result of which the oil particles are thrown to the sieve catcher, the oil is separated from the air and enters the interwall space of the housing and the sieve catcher, and flows down into the oil sump, from where it is drained using a tap. After that, it can be sent for processing, or, after cleaning, enter the pump lubrication system. The oil-free air continues to move over the surface of the screw winding, and due to the change in the pitch of the screw winding, the air decreases its speed, as a result of which the noise level decreases and oil content is cleaned more efficiently. Air passes to the top cover and enters the environment through the outlet pipe. The work establishes a relationship between the pump performance and the design parameters of the muffler filter. In production conditions, it was investigated that the separation of oil from air in the proposed muffler is 93-95%, and the amount of noise reduction is 15-22 dB. The use of a muffler filter implies a decrease in the productivity of the vacuum pump, which is about 1 m3/h, compared to the serial one - 1.28 m3/h. To introduce the muffler filter into production, it is advisable to use the relationship between the performance of the vacuum pump and the structural parameters of the muffler filter and to develop a division into standard sizes.

Boundary Control for Suppressing Chaotic Response to Dynamic Hydrogen Blending in a Gas Pipeline

It is known that periodic forcing of nonlinear flows can result in a chaotic response under certain conditions. Such non-periodic and chaotic solutions have been observed in simulations of heterogeneous gas flow in a pipeline with periodic, time-varying boundary conditions. In this paper, we examine a proportional feedback law for boundary control of a parabolic partial differential equation system that represents the flow of two gases through a pipe. We demonstrate that periodic variation of the mass fraction of the lighter gas at the pipe inlet can result in the chaotic propagation of gas pressure waves, and show that appropriate flow control can suppress this response. We examine phase space solutions for the single pipe system subject to boundary control, and use numerical experiments to characterize conditions for the controller gain to suppress chaos.

Effects of Alien Organisms on Growth of Common Carp, Cyprinus carpio Cultivated in Earthen Ponds

The experiment was conducted at Agricultural Research Station- Aquaculture Unit- Agriculture College- Basrah University in six earthen ponds (600 m3). The stady inclouding of alien organizms effect on growth of common carp Cyprinus carpio. Using an agricultural shadow as a filtering fabric was put in inlets pipes (T1), while T2 without filters. Fishes was daily feeding by a commercial sinking pellets manufactured by Agricultural Consultant Office belonging to Agriculture College, With a ratio of 3% from fishes weight. Total length and weight of fishes were measured at the beginning and at the end of the experiment. The weight of subsamples for fishes were taken periodically and daily feed changed after each weighing. At the end of the experiment the alien organism in all ponds were collected, classified and weighed individualy except shrimp. Results of current experiment revealed that there were significant differences (P≤0.0.5) in final weigh, wight increment, daily growth rate and feed conversion rate between fishes reared in ponds with and without filter. These differences may be related to differences in numbers and weighs of alien organisms in these ponds (97 individuals of six fish species in ponds without filter comparing with two individuals of one fish species in ponds with filter, and also 16314 g of shrimp in ponds without filter comparing with 440 g in ponds with filter). From the results of the current experiment, it can be concluded that culturist must used filters in inlet pipes of their ponds to prevent or reduced the entering of alien organizms to these ponds.

Study on transient characteristics of pipeline under centrifugal pump shaft stuck condition

In the pump system, the water hammer effect generated by the shaft stuck accident will cause great harm to the pump and piping system. In order to reveal the transient characteristics of the pipeline during the transition process of vane-pump shaft stuck, three shaft stuck time of Δt = 0.5 s, Δt = 1 s and Δt = 1.5 s is tested by building a closed test bench of centrifugal pump. And establish a 1:1 closed system three-dimensional model to study the external characteristics and internal flow field changes of the pump and piping system during the transition process of the shaft stuck. The study shows that: The rotational speed curves are non-linearly decreasing; the patterns of change in flow rate show a roughly exponential function trending downward; the heads during the shaft stuck will fall rapidly and reach the reverse extreme value. For the pump inlet piping system, the pressure of each place in the speed down to 0 rpm before the peak, the pressure of the outlet pipeline is always down to the reference pressure. Under the same shaft stuck condition, the pressure change in each place of the inlet piping system is basically the same, and the pressure reaches the peak at the same time. The maximum pressure of the inlet and outlet piping is at the rear 3/4 of the elbow. The closer to the face of the inlet and outlet of the elbow, the greater the load force applied; with the elbow as the demarcation, the pressure gradually increases along the flow direction. By revealing the transient mechanism of system piping during centrifugal pump shaft stuck transient process, it provides a reference basis for the design and accident safety assessment of vane-type pumping system.

Unsupervised Machine Learning Clustering of Seismic and Infrasound Data Quality Metrics

Abstract Developing techniques for improving quality control (QC) schemes to catch seismic and infrasound data defects continues to be an area of active research. Selecting universal thresholds for the automation of data quality (DQ) checks is an efficient way to find QC issues, but these thresholds may not apply well to multiple stations with varying DQ characteristics. In addition, these thresholds may not catch subtle changes in DQ parameters that still indicate problems. Machine learning can be an alternative way of diagnosing QC issues. K-means clustering, an unsupervised machine learning clustering algorithm, has been effectively used in the past for geophysical pattern exploration. This study furthers k-means applications to DQ analysis through clustering on DQ metrics derived from day-long segments of nuclear explosion monitoring data. Our k-means implementation on broadband seismometer DQ metrics separately clustered mass recenters, calibrations lasting at least one hour, and days without either. Applying this technique to infrasound DQ metrics revealed clusters related to physical issues at the stations, such as missing back volume screws and the flooding of ported pipe inlets. These are both examples of QC issues that are difficult to diagnose or detect through the thresholding of metrics or by inspecting waveforms and spectra. Our results show that k-means clustering can be a useful QC tool in exploring DQ patterns to assist analyst review of station operation and maintenance. The learned knowledge from this exploration can then inform a thresholding workflow on how to tailor to individual stations, or the k-means model could classify data directly.

Phase transition cooling structure towards the wing antenna of hypersonic vehicle

In order to optimize the heat dissipation efficiency of the wing antenna of a hypersonic vehicle, a comprehensive performance-based investigation of active cooling of the wing antenna unit is proposed, taking into account multiple factors. The volume of fluid (VOF) model is employed to simulate and examine the behavior of bubbles and thermal performance on the model surface with respect to the pipe inlet, pipe outlet, and pipe spacing. Furthermore, the heat dissipation efficiency of the wing antenna structure is validated using a quartz lamp as the heat source. The comprehensive performance factor is able to balance the relationship between pressure drop and heat transfer. The simulated heat dissipation efficiency shows a high level of agreement with experimental testing. These results indicate that an appropriate coolant flow rate and flux can effectively provide the degree of phase change, and vapor can only provide effective heat dissipation within a suitable range. Conversely, in situations with excessive or insufficient bubbles, heat cannot be effectively dissipated, thereby reducing the heat dissipation efficiency.

Low-frequency fluctuation propagation of rotating stall in the centrifugal compressor and pipe system

The characteristic signal judgment of rotating stall in a centrifugal compressor is necessary to avoid the compressor becoming instability in operation. This study investigates rotating stall in a centrifugal compressor and pipe system using experimental and numerical simulation methods. In the experiment, a low-frequency (approximately 10% of the impeller's rotational frequency) pressure fluctuation is observed in the inlet and outlet pipes as the pressure ratio curve declined at small flow rate. The frequency spectrum results of different measuring locations suggest that the low-frequency disturbance is in the flow direction within the pipe system during rotating stall. To further analyze this pressure fluctuation, a transient numerical simulation of the centrifugal compressor with plenum model is conducted. Rotating stall can be captured by the numerical model, and the low-frequency pressure fluctuation is also observed in the transient simulation, aligning with the experimental results. The periodic evolution of the tip leakage vortex influences the flow in the impeller passage, causing a fluctuation in the flow direction that propagates upstream and downstream as revealed by flow field analysis. The low-frequency pressure fluctuation in the inlet and outlet pipe system is a characteristic signal, which can be a new stall judgment of rotating stall in the operation of centrifugal compressor.

Low-Frequency Discontinuous Noise Diagnosis and Reduction of Air Conditioner Outdoor Unit

Abnormal discontinuous low-frequency noise occurs in the outdoor unit when the air conditioner is operating at 86~96 Hz. This noise has the characteristics of low frequency, strong penetration, long transmission distance, and poor sound quality, which can cause serious noise pollution. In order to reduce the low-frequency noise of the outdoor unit of the air conditioner, the discontinuous noise frequency is first located by testing the time-domain and frequency-domain maps of the noise. It is then compared with the frequency of fan rotation noise and structural radiation noise. It is found that the discontinuous noise is caused by the coupling of fan rotation noise and structural radiation noise. It is found that low-frequency noise improvement is significant when the frequency difference between two noise peaks is greater than 8 Hz or when a single noise peak is less than 25 dB(A) by studying the methods of frequency modulation and amplitude modulation of noise peaks. By adjusting the fan speed from 930 rpm to 940 rpm, the problem of 94 Hz noise is solved. Then, through testing the natural frequencies of the pipe and shell, it is found that the natural frequencies of the pipe are close to the excitation frequencies. The structural radiation noise is mainly caused by the pipe. Modal analysis is conducted on the pipe. When the normal boundary with the condenser and the normal boundary with the valve of the pipe is constrained by springs, the simulated values are closer to the measured values. Finally, structural optimization design is carried out on the pipe. When the U-tube of the exhaust pipe is shortened by 30 mm, a 30 g mass block is added to the cold inlet pipe, and a 97 g mass block is added to the lower part of the valve pipe of the suction pipe. The discontinuous noise of the optimized prototype is significantly improved.