Multiple Tube Research Articles

Study on buckling-restrained braces using multiple round steel core bars

This study proposes a novel buckling-restrained brace (BRB) using multiple round steel core bars to increase the feasible strength of BRBs utilizing steel bars with roll-threaded screw ends. The buckling restraining members of the proposed BRB consists of multiple primary tubes and a secondary tube. The primary tube directly restrains the buckling of each core bar, and the secondary tube restrains the buckling of the primary tube through spacers. This paper first describes the configuration of the proposed BRB and the design method of buckling restrainers, in which the spacer spacing is assumed to be the buckling length of the primary tube. Subsequently, cyclic loading tests of three specimens with different spacer spacing are presented to demonstrate the mechanical behavior of the proposed BRB, such as the hysteresis behavior, axial force, and bending moment of the primary tubes. The test results indicated that fulfilling the requirement of spacer spacing is essential for achieving stable behavior of the primary tubes and steel core bars. Finally, finite element analyses of buckling-restrained units of the proposed BRB with different combinations of primary tubes and spacer spacing are presented to verify the design method. The results of the parametric analyses indicated that the proposed design formula can provide a conservative evaluation of the stability of the primary tube.

P245 Arthrinium species, a filamentous ascomycetes isolated from samples of human cutaneous infections-report from a medical mycology laboratory of Assam, North-East India

Poster session 2, September 22, 2022, 12:30 PM - 1:30 PMObjectivesThis study aims to report the isolation of closely related Arthrinium species from superficial skin lesions of five cases from a medical mycology laboratory of Assam, North East India.MethodsThe lesions were decontaminated with 70% ethanol and skin scrapings were collected on a sterilized glass plate. Direct mounts were prepared in 10%-20% KOH and cultures were put in Saboraud's Dextrose Agar with antibiotics, 5% sheep blood agar, and dermatophyte test medium (Himedia, India). Plates and tubes were incubated as per standard mycological techniques described. Molecular identification was done using ITS sequence analysis using ITS1 and ITS4 universal primers.ResultsDirect mount showed presence of hyphae with arthrospores in 3/5 cases. In one case, fungal hyphae was seen along with spore-like oval or round structures of about 3-4 μm diameter. Pure growth was seen after 7-14 days in multiple culture tubes in all five cases. Colonies were white, downy initially becoming white, and floccose on further incubation. Subculture on PDA in all the cases for 15-20 days revealed black, round, and oval spores of 3-5 μm suggesting Arthrinium spp.The taxonomical identification was done by constructing a phylogenetic tree of the ITS sequences of the Arthrinium isolates of this study along with reference Arthrinium strains and Seiridium phylicae as the outgroup taxa.The phylogenetic analysis clustered the isolates of this study into closely related Arthrinium species.ConclusionThe genus Arthrinium belonging to the family Apiosporaceae, class Sordariomycetes which comprises of a group of filamentous ascomycetes fungi is rarely reported from human infections. We are reporting closely related Arthrinium spp from five cases of skin lesions from Assam, North East India. Three of the 5 cases hailed from tea garden areas of Assam. Arthrinium isolation in clinically significant cases and in multiple tubes may not be disregarded as a contaminant.

Melting dynamics analysis of a multi-tube latent heat thermal energy storage system: Numerical study

This numerical study investigates the melting dynamics of paraffin wax as a phase change material (PCM) in a multi-tube latent heat thermal energy storage system (MT-LHTESS). The performance of an arrangement with four tubes is compared with a concentric single tube arrangement keeping the same cross-section area of heat transfer fluid tubes and the same PCM quantity. Four longitudinal fins of two types are also incorporated to further improve the melting. Thirteen cases with different arrangements of tubes and fins are compared in this study. The study attempts to select a suitable arrangement of the tubes. A two-dimensional enthalpy-porosity model in ANSYS-Fluent is used to solve the governing equations. The melting results are depicted as the contours of liquid fraction, temperature, and flow streamlines. The transient performance is assessed based on progress plots of liquid fraction and average domain velocity. It is observed that splitting into multiple tubes and using fins enhance the melting performance. The generation and coalescence of small vortices in the molten PCM accelerate the melting performance. The staggered array, larger eccentricity, and (+ type) finned tubes outperform their counterparts. The lowest melting time is observed in Case 2(+), having four staggered tubes, at 30 mm eccentricity, and with (+ type) fins. This case takes 75 min for complete melting, and 1411.1 kJ/m heat at a rate of 322 W/m is stored. The melting time gets reduced by 53.3–71.1% using four tubes and by 65.78–83.33% using finned four tubes as compared to the single tube case.

Review: Echo’s Chambers: Architecture and the Idea of Acoustic Space

Review: <i>Echo’s Chambers: Architecture and the Idea of Acoustic Space</i>

Numerical simulation on shell-side flow pattern transition and heat transfer of non-azeotropic refrigerant mixture

The non-azeotropic hydrocarbon refrigerant mixture flowing across shell-side of spiral wound heat exchanger is widely used in liquefied natural gas production industry. However, the phase-change heat transfer mechanism is still lack of thorough understanding. A numerical model is presented for simulating evaporation heat transfer of non-azeotropic hydrocarbon refrigerant mixture, CH4/C2H6, across multiple spiral wound tubes. Volume of Fluid model (VOF) was used to obtain liquid–vapor interface. The heat and mass transfer rates for each component were given as source terms. Thermophysical properties of the mixture were given using mixing laws in the literature. A flow pattern map was developed based on simulation results. The flow pattern transition and heat transfer were analyzed for the mixture with several component mixing ratios. With increasing vapor quality, pure ethane and methane-ethane mixture appear different flow patterns. The pure ethane has smoother liquid film on the tube wall than the methane-ethane mixture. The increasing of methane promotes the flow pattern transition. With vapor quality of 0.2–0.3, falling film flow transfers to shear flow. Shear flow transfers to spray flow for vapor quality of 0.7–0.8, where the heat transfer coefficient starts to decrease for methane-ethane mixture. For falling film flow, the heat transfer coefficient of pure ethane is higher than the methane-ethane mixture. The outcomes may help spiral wound heat exchanger design and evaluation for liquefied natural gas production.

Coliform pollution mapping in major watersheds along Jhelum River Basin of Kashmir Himalaya.

Coliform pollution for the last three decades in major river systems of the world has resulted in far ranging impacts on water quality. In this context, the present study aimed to assess the levels of indicator bacteria like total Coliform (TC), fecal Coliform (FC) and fecal Streptococcus (FS) in major watersheds of Kashmir valley. Sampling was carried out for a period of 2 years (summer 2017 to spring 2019) along several upstream, midstream and downstream reaches of Jhelum River Basin (JRB), while analysis was carried out by multiple tube fermentation technique involving Most Probable Number (MPN). Major highlights of the results revealed high levels of TC, FC and FS among downstream sites with pronounced seasonal variations between summer and winter. TC was highest at all the reaches and during all the seasons followed by FC and FS. Non-metric multidimensional scaling (NMDS) revealed more variation in Coliform count among reaches as compared to seasons. Mantle test revealed that environmental factors like observable environmental pressure (OEP) (r: 0.235, p < 0.0001), DO (r: 0.2815, p < 0.0001) and temperature (r: 0.04419, p = 0.0104) had prominent effect on Coliform distribution as compared to geographical factors. The study thus highlights the prevalence of Coliform bacteria along JRB resulting from fecal sources. Due to growing urbanization and lack of adequate sewage treatment facilities, there is an increase in the levels of Coliform bacteria along downstream reaches especially those residing within lowerJhelum and Dara watershed, which could jeopardize water quality and public health.

A comprehensive study on melting enhancement by changing tube arrangement in a multi-tube latent heat thermal energy storage system

In this study, the paraffin wax's melting dynamics in a multi-tube latent heat thermal energy storage system are investigated. The performance of ten arrangements of five heat transfer fluid tubes is compared. The radial eccentricity of four planetary tubes is varied around a fixed central tube. The study aims to find an appropriate arrangement of multiple HTF tubes keeping the same PCM content and heating surface. A simplified two-dimensional computational domain was considered, an enthalpy-porosity based melting model was designed, and the governing equations were solved using ANSYS-Fluent. The melting sequence in various cases is represented as the liquid fraction contours, flow streamlines, and temperature contours. The performance of proposed designs is assessed on the basis of transient plots of liquid fraction, average domain velocity, and heat flux at the outer surface of the heat transfer fluid tube. It is observed that the melting dynamics are greatly influenced by the tube arrangement. The coalescence of small vortices and the intermixing of different temperature layers accelerate the melting. It is found that the tubes in the top half should be placed closer to the center to delay thermal stratification, and in the bottom half should be placed deeper into the poor melting zone. The staggered arrangement of planetary tubes outperforms the inline arrangement at given eccentricities. The fastest and slowest melting is realized by Case 9 and Case 1, which take 128 and 269 min, respectively, for melting. The proposed designs can store 1450 kJ/m of energy with 98 % theoretical efficiency.

Rapid Nucleic Acid Extraction for Aquatic Animal DNA Virus Determination Using Chelex 100 Resin via Conventional PCR and Digital Droplet PCR Detection

Simple SummaryConvenient, fast, and high-quality nucleic acid extraction methods are urgently needed in molecular diagnostic testing for viral pathogens in aquaculture. We developed a viral DNA extraction method from diseased tissues and cells using the Chelex 100 resin solution workflow. The only extraction reagents required are the Chelex 100 resin and phosphate-buffered saline. The whole extraction process only takes about 15 min from the tissue homogenate to obtain the DNA. The concentration of extracted DNA is at least 100 ng/µL. This methodology has clear benefits in terms of cost and time saving compared to the commercial kit extraction for aquatic animal DNA virus determination by PCR in the laboratory. In addition, the simplified method using Chelex 100 resin with a pH value of 10–11 presented excellent results in PCR application and could be a standard for the DNA extraction for DNA virus testing in the future.Molecular diagnostic testing for viral pathogens is crucial in aquaculture. The efficient and convenient preparation of pathogenic microbial nucleic acids is the basis of molecular diagnosis. Here, we developed a simplified deoxyribonucleic acid (DNA) extraction method from aquatic animal DNA viruses using the Chelex 100 resin. The nucleic acid was extracted from infected tissues and cell culture for the detection of three common aquatic viral pathogens (CEV, CyHV-2, and GSIV). We compared the extraction effects of a current commercial kit extraction method and the Chelex 100 resin extraction method according to nucleic acid concentration, conventional polymerase chain reaction (PCR), and digital droplet PCR (ddPCR). The results indicated that both extraction procedures could obtain high-quality nucleotide samples. Extracting DNA using the Chelex 100 resin led to better detective efficiency for ddPCR molecular diagnostic testing. The whole process took less than 20 min, and only Chelex 100 resin solution was added to the tissues or cells without multiple tubes being transferred several times. The extracted DNA concentration and the detection sensitivity were high. These results indicated that the Chelex 100 resin solution has the advantages of speed, efficiency, and economy compared to the commercial kit. In addition, the higher pH value (10–11) of the Chelex 100 resin solution markedly improved the detection sensitivity compared to a lower pH value (9–10). In conclusion, the comparison of the Chelex 100 Resin and commercial viral DNA extraction kits revealed the good performance of the Chelex 100 resin solution at pH 10–11 in DNA extraction for PCR amplification from aquatic animal viral samples of tissues and cells in molecular diagnostic testing. It is both rapid and cost-effective.

A universal strategy for flexible, efficient and programmable crashworthiness under quasi-static and dynamic loadings based on plastic deformation of metals

Cellular materials and mechanical metamaterials respectively display desirable efficiency and programmability in engineering protection, however, the means to combine their advantages poses a challenge. To break this limit, a universal strategy based on plastic deformation of metals is established to realize flexible, efficient and programmable crashworthiness, which is implemented in three steps. Firstly, cellular material is discretized as multiple self-locked tubes, endowing it with convenient assembling and disassembling processes as well as flexible property tunability to adapt to load characteristics. Then, perforated design is executed mainly to induce efficient progressive buckling mode and superior crashworthiness by creating geometry discontinuities. Finally, nested design is employed to promote space utilization and plateau stress. More critically, multiple step functions with target characteristics can be introduced on stress–strain curve to obtain programmability by controlling parameters of fillers. The windmill-inspired system made of 316L stainless steel is taken as the instance to implement the strategy, and both quasi-static and dynamic loading conditions are considered. The strategic feasibility is validated by experiments and simulations, and specific energy absorption, energy absorption efficiency and force efficiency respectively increase by 53.8%, 13.5% and 77.9%. This research opens a new avenue for combing efficient mechanical behavior and flexible property programmability.

Open-top light-sheet imaging of CLEAR emulsion for high-throughput loss-free analysis of massive fluorescent droplets

Digital droplet PCR (ddPCR) is classified as the third-generation PCR technology that enables absolute quantitative detection of nucleic acid molecules and has become an increasingly powerful tool for clinic diagnosis. We previously established a CLEAR-dPCR technique based on the combination of CLEAR droplets generated by micro-centrifuge-based microtubule arrays (MiCA) and insitu 3D readout by light-sheet fluorescence imaging. This CLEAR-dPCR technique attains very high readout speed and dynamic range. Meanwhile, it is free from sample loss and contamination, showing its advantages over commercial d-PCR technologies. However, a conventional orthogonal light-sheet imaging setup in CLEAR d-PCR cannot image multiple centrifuge tubes, thereby limiting its widespread application to large-scale, high-speed dd-PCR assays. Herein, we propose an in-parallel 3D dd-PCR readout technique based on an open-top light-sheet microscopy setup. This approach can continuously scan multiple centrifuge tubes which contain CLEAR emulsions with highly diverse concentrations, and thus further boost the scale and throughput of our 3D dd-PCR technique.

CFD analysis and scale up of a baffled membrane reactor for hydrogen production by steam methane reforming

Catalytic membrane reactor (CMR) represents an intensified process that combines the reaction and separation steps. For a high level of productivity, multiple membrane tubes are placed in a CMR, which can lead to the problem of concentration and temperature gradients. This study explores the idea of placing baffles inside the CMR, which is called baffled membrane reactor (BMR). Representative CMR and BMR are compared using computational fluid dynamics (CFD) simulations. First, the CFD model of a single-tube CMR is validated with the published experimental data. The results for a 4-tube CMR and BMR (with 14-baffles) reveal that the baffles lead to complex flow patterns, regions with elevated pressure, reduced concentration gradients and reduced temperature drops. The BMR’s performance is less sensitive to an increase in gas hourly space velocity than that of the CMR. Simulations of a larger-scale BMR shows that the performance improvement over the CMR is retained.

Development of a 27-color panel for the detection of measurable residual disease in patients diagnosed with acute myeloid leukemia.

Acute myeloid leukemia (AML) measurable residual disease (MRD) evaluated by multiparametric flow cytometry (MFC) is a surrogate for progression-free and overall survival in clinical trials and patient management. Due to the limited number of detection channels available in conventional flow cytometers, panels used for assessing AML MRD are typically split into multiple tubes. This cripples the simultaneous and correlated assessment of all myeloblast measurements. In response, we prototyped a single-tube 27-color MFC assay for the evaluation of AML MRD, incorporating all recommended markers. Marrow aspirates from 22 patients were processed for analysis using full spectrum flow cytometry (FSFC). The signal resolution of each marker was compared between samples stained with single antibody vs. the fully stained panel. The analytical accuracy for quantifying hematopoietic cells between our established 8-color assay and the new 27-color method were compared. Variations within an operator and between separate operators were assessed to evaluate the assays reproducibility. The limited of blank (LOB), limit of detection (LOD), and lower limit of quantification (LLOQ) of the 27-color method were empirically determined using limiting dilution experiments. The stability of antibody cocktails over a period of 120 h was also studied using cryopreserved marrow cells. The stain indices for all antibodies were lower in the fully stained panel compared to cells stained with one antibody but clear separations between negative and positive signals were achieved for all antibodies. Our results demonstrated a high concordance between the established 8-color method and the new 27-color assay for enumerating myeloblasts and MRD interpretation within and between operators. The data further showed that the single-tube 27-color assay easily achieved the minimum required detection sensitivity of 0.1%. When antibodies were combined, however, expression intensity of some antigens deteriorated significantly when stored. Our single-tube 27-color panel is a suitable, high sensitivity flow cytometric approach that can be used for AML MRD testing, which improves the correlation of aberrant antigens and detection of asynchronous differentiation patterns. Based on the stability study, we recommend the full panel be made prior to staining.

Recurrent Catamenial Pneumothorax After Multiple Chest Tube Placements, Pleurodesis and Vats

Catamenial pneumothorax is characterized by spontaneous pneumothorax occurring 72 hours before or after onset of menstruation in a reproductive aged woman. It is an extremely rare condition, and although generally thought to be due to abnormal migration of endometrial tissue to the pleural space, the mechanism of this migration is unclear. We present a case of recurrent catamenial pneumothorax after chest tube placements, pleurodesis and videoassisted thoracoscopic surgery (VATS).

Numerical investigation on melting and energy storage density enhancement of phase change material in a horizontal cylindrical container

Thermal energy storage (TES) plays a significant role in storing heat energy during the availability of a source. The phase change material (PCM) storage density is high, but its meager thermal conductivity leads to ineffective heat transfer. This mathematical modeling work simulates two different heat transfer tube (HTT) arrangements in a horizontal cylindrical container to melt the PCM using the enthalpy-porosity method. Case-1 with a single HTT at the centroidal axis and Case-2 with multiple tubes spread radially. Cases-1 and 2 are observed with melting and solidification duration of 39.8 and 184 minutes, and 69.83 and 292.5 minutes respectively. Case-1 has a shorter melting and solidification time because of the optimal HTT location. Case-2 is observed with a high heat storage density of 224.95 MJ/m3, compared to Case-1 with 224.571 MJ/m3. Nusselt number is higher for Case-2 (385.86) during charging and higher for Case-1 (208) during discharging. Nusselt number initially varies for both cases due to effective heat convection at the start; however, Case-1 has a shorter melting duration with its energy density lower than the Case-2. Based on the obtained results, it could be suggested that Case-1 could be applicable when simultaneous heat transfer requires less energy storage and a faster melting rate, while Case-2 could be used in places that demand a higher storage density.

Experimental Investigation of Special-Shaped Concrete-Filled Square Steel Tube Composite Columns with Steel Hoops under Axial Loads.

Special-shaped concrete-filled steel tube (SS-CFST) columns can be embedded in the wall, thus preventing the columns from protruding. This feature makes it popular in steel residential buildings. This paper proposes a new special-shaped concrete-filled square steel tube (SS-CFSST) composite column composed of multiple square steel tubes connected by steel hoops to form L-, T- or cross-shaped sections. Eight specimens were tested under axial loads with section shape, construction method, slenderness ratio, steel tube thickness, and steel strength as variation parameters. The structural performance, such as failure modes, peak load, load–displacement curves, load–strain curves, and Poisson’s ratio of the steel tubes, were analyzed. The tests illustrated that the failure modes of hoop-type specimens and weld-type stub columns were mainly the local buckling of steel tubes and bending failure, and those of the weld-type slender columns were mainly overall bending failure. The load-carrying capacity of the hoop-type specimen was higher than that of the weld-type specimen with the same cross-sectional dimensions and slenderness ratio. Next, the stress–strain relationship model of core concrete in the SS-CFSST composite column was established by considering the restraint effect of the connection coincidence area of steel tubes and steel hoops on concrete. Additionally, the finite element model (FEM) of the column was established using this constitutive model. By comparing the failure modes, load–strain curves and bearing capacities obtained from the tests and FEM, the established FEM can accurately evaluate the mechanical properties of SS-CFSST composite columns with steel hoops under axial compression.

Characterization of a new ultra-high pressure shock tube facility for combustion and propulsion studies.

A new shock tube facility has been designed, constructed, and characterized at the University of Central Florida. This facility is capable of withstanding pressures of up to 1000 atm, allowing for combustion diagnostics of extreme conditions, such as in rocket combustion chambers or in novel power conversion cycles. For studies with toxic gas impurities, the high initial pressures required the development of a gas delivery system to ensure the longevity of the facility and the safety of the personnel. Data acquisition and experimental propagation were implemented with remote access to ensure safety, paired with a LabVIEW- and Python-based user interface. Thus far, test pressures of 270 atm, blast pressures of 730 atm, and temperatures approaching 10 000K have been achieved. The extreme limitations of this facility allow for emission spectroscopy to be performed during the oxidation of fuel mixtures, e.g., alkanes diluted in argon and carbon dioxide. Ignition delay times were determined and compared to simulations using chemical kinetic mechanisms. The design, experimental procedures, processes of analysis, and uncertainty determination are outlined, and typical pressure profiles are compared with a new gas dynamics solver and empirical correlations developed across multiple shock tube facilities. Preliminary reactive mixture analyses are included with further investigation of the mixtures outlined.

Seasonal assessment of Faecal Contamination in groundwater in rural areas of Goharganj, district Raisen (Madhya Pradesh), India

In rural areas, bacterial contamination in drinking water quality is a growing concern throughout the world.The present study dealt with seasonal assessment of faecal contamination in rural areas of Goharganj,district Raisen. Forty sites were sampled and analysed for T. coliform, F. coliform and F. streptococcus byusing multiple tube fermentation technique for premonsoon, postmonsoon and winter season for a periodof two years from 2018-2020. The average bacterial count (MPN/100 ml) of T. coliform was found to be 4.61,5.31, 5.08, and for F. coliform 2.95, 3.45, 3.37 and for F. streptococcus 1.8, 2.21, 1.94 for premonsoon,postmonsoon and winter season respectively. The highest bacterial count was found in postmonsoon seasonpreceded by winter and premonsoon season. This was construed as a major concern for the humans andposed a health risk for the consumers of such contaminated drinking water. In near future, the rural areasmay have community programmes for the eradication of unhygienic practices and safe drinking water.

Slip-Spring Hybrid Particle-Field Molecular Dynamics for Coarse-Graining Branched Polymer Melts: Polystyrene Melts as an Example.

The topology of chains significantly modifies the dynamical properties of polymer melts. Here, we extend a recently developed efficient simulation method, namely the slip-spring hybrid particle-field (SS-hPF) model, to study the structural and dynamical properties of branched polymer melts over large spatial-temporal scales. In the coarse-grained SS-hPF simulation of polymers, the bonded potentials are derived by iterative Boltzmann inversion from the underlying fine-grained model. The nonbonded potentials are computed from a density functional field instead of pairwise interactions used in standard molecular dynamics simulations, which increases the computational efficiency by a factor of 10-20. The entangled dynamics is lost due to the soft-core nature of density functional field interactions. It is recovered by a multichain slip-spring model that is rigorously parametrized from existing experimental or simulation data. To quantitatively predict the relaxation and diffusion of branched polymers, which are dominated by arm retraction rather than chain reptation, the slip-spring algorithm is augmented to improve the polymer dynamics near the branch point. Multiple dynamical observables, e.g., diffusion coefficients, arm relaxations, and tube survival probabilities, are characterized in an example coarse-grained model of symmetric and asymmetric star-shaped polystyrene melts. Consistent dynamical behaviors are identified and compared with theoretical predictions. With a single rescaling factor, the prediction of diffusion coefficients agrees well with the available experimental measurements. In this work, an efficient approach is provided to build chemistry-specific coarse-grained models for predicting the dynamics of branched polymers.

Constrained Nonlinear and Mixed Effects Integral Differential Equation Models for Dynamic Cell Polarity Signaling.

Polar cell growth is a process that couples the establishment of cell polarity with growth and is extremely important in the growth, development, and reproduction of eukaryotic organisms, such as pollen tube growth during plant fertilization and neuronal axon growth in animals. Pollen tube growth requires dynamic but polarized distribution and activation of a signaling protein named ROP1 to the plasma membrane via three processes: positive feedback and negative feedback regulation of ROP1 activation and its lateral diffusion along the plasma membrane. In this paper, we introduce a mechanistic integro-differential equation (IDE) along with constrained semiparametric regression to quantitatively describe the interplay among these three processes that lead to the polar distribution of active ROP1 at a steady state. Moreover, we introduce a population variability by a constrained nonlinear mixed model. Our analysis of ROP1 activity distributions from multiple pollen tubes revealed that the equilibrium between the positive and negative feedbacks for pollen tubes with similar shapes are remarkably stable, permitting us to infer an inherent quantitative relationship between the positive and negative feedback loops that defines the tip growth of pollen tubes and the polarity of tip growth.

Experimental studies on the performance of multiple tubes bubble pump with R134a-TEGDME

A closed multiple lifting tube bubble pump setup with pressure difference has been built to explore the vapor generating and liquid pumping performance of diffusion gas generating bubble pump, which is used in diffusion absorption heat transformer. In all the experiments, R134a and TEGDME were employed as diffusion gas and absorbent. The influences of concentration (the mass fraction of R134a in the solution), motive head, lifting tube number and heat input on the performance of bubble pump were investigated. The R134a mass flow rate was used to evaluate vapor generating performance, while the dilute solution mass flow rate and pumping ratio were used to evaluate liquid pumping performance. The experimental results showed that: (1) the increase of concentration was beneficial to generation of R134a which resulted in larger R134a flow rate and lower generating temperature, and it also led to larger dilute solution flow rate; (2) larger motive head led to larger R134a flow rate and smaller pumping ratio, but resulted in higher pressure and generating temperature; (3) the variations of R134a flow rate, dilute solution flow rate and pumping ratio were not varied when lifting tube number changed, but the upper limit of R134a and dilute solution flow rate increased significant with the increase of lifting tube number. It was concluded that the bubble pump with multiple lifting tube had little limitation to the fluid flow rate. The results obtained in the paper will be helpful to the further study of diffusion gas generating bubble pump.