kPa Pressure Drop Research Articles

Spray Cooling With Ammonia on Microstructured Surfaces: Performance Enhancement and Hysteresis Effect

Experiments were performed to investigate spray cooling on microstructured surfaces. Surface modification techniques were utilized to obtain microscale indentations and protrusions on the heater surfaces. A smooth surface was also tested to have baseline data for comparison. Tests were conducted in a closed loop system with ammonia using RTI’s vapor atomized spray nozzles. Thick film resistors, simulating heat source, were mounted onto 1×2 cm2 heaters, and heat fluxes up to 500 W/cm2 (well below critical heat flux limit) were removed. Two nozzles each spraying 1 cm2 of the heater area used 96 ml/cm2 min(9.7 gal/in.2 h) liquid and 13.8 ml/cm2 s(11.3 ft3/in.2 h) vapor flow rate with only 48 kPa (7 psi) pressure drop. Comparison of cooling curves in the form of surface superheat (ΔTsat=Tsurf−Tsat) versus heat flux in the heating-up and cooling-down modes (for increasing and decreasing heat flux conditions) demonstrated substantial performance enhancement for both microstructured surfaces over smooth surface. At 500 W/cm2, the increases in the heat transfer coefficient for microstructured surfaces with protrusions and indentations were 112% and 49% over smooth surface, respectively. Moreover, results showed that smooth surface gives nearly identical cooling curves in the heating-up and cooling-down modes, while microstructured surfaces experience a hysteresis phenomenon depending on the surface roughness level and yields lower surface superheat in the cooling-down mode, compared with the heating-up mode, at a given heat flux. Microstructured surface with protrusions was further tested using two approaches to gain better understanding on hysteresis. Data indicated that microstructured surface helps retain the established three-phase contact lines, the regions where solid, liquid, and vapor phases meet, resulting in consistent cooling curve and hysteresis effect at varying heat flux conditions (as low as 25 W/cm2 for the present work). Data also confirmed a direct connection between hysteresis and thermal history of the heater.

Delivery of salbutamol and of budesonide from a novel multi-dose inhaler AirmaxTM

A novel multi-dose inhaler has been developed to closely approach the characteristics of an “ideal” inhaler. The new device, AirmaxTM, uses proprietary technologies known as the X-ACTTM system to provide accurate and consistent dosing and excellent lung deposition—even at low inspiratory flow rates—combined with ease of use by the patient. Dose delivery was close to label claim, with relative standard deviation of typically around 5% for through-life emitted mass and around 10% for dose per actuation. At a flow rate (60–70 l/min), which corresponds to 4 kPa pressure drop across the device, the mean fine particle (<5 μm) dose (FPD) from 100, 200 and 400 μg strength budesonide AirmaxTM was around 46, 98 and 244 μ g, respectively. The mean FPD from 100 μg strength salbutamol AirmaxTM was approximately 50 μg at the same flow rate. At 30 l/min, the delivered dose from AirmaxTM is over 85% label claim with fine particle fraction of over 35%. Performance was unaffected by shaking or orientation, provided the device was not used completely upside down, and priming was not required. There was no change in dose content uniformity and aerodynamic particle-size distribution after the devices have been stored unwrapped at 30°C/60% RH up to 24 months. Airmax is robust, portable and intuitive to use.

Synthesis and Permeation Properties of SAPO-34 Tubular Membranes

A SAPO-34 membrane was prepared on an alumina tubular support. This membrane appears to exhibit molecular sieving properties with permeances that decrease as the kinetic diameter increases. The room-temperature permeances of H2 and n-C4H10 were 2.4 × 10-8 and 1.9 × 10-10 mol/(m2 s Pa), respectively, and the permeances were in the order H2 > CO2 > N2 > CH4 > n-C4H10. As the temperature increased, the single gas permeances of H2 and N2 exhibited minima, whereas the permeance of CO2 decreased and that of CH4 increased. As the pressure increased with a constant pressure drop across the membrane, the permeances of H2, CO2, N2, and CH4 decreased. The H2/CH4, CO2/CH4, H2/N2, and CO2/N2 ideal selectivities at 300 K and 270 kPa feed pressure with a 138 kPa pressure drop were 25, 19, 7.4, and 5.7, respectively, and these selectivities decreased with increasing temperature and increased with increasing pressure. The ideal selectivity of N2/CH4 was 3.4 at the same conditions and decreased with increasing temperature and increasing pressure. The H2/CO2 ideal selectivity was 1.3 at the same conditions and increased with increasing temperature and pressure. At 270 kPa feed pressure and 138 kPa pressure drop, the CO2/CH4 mixture selectivity was 30 at 300 K and 3.4 at 470 K.

AVERAGE SPECIFIC CAKE RESISTANCE DETERMINED IN the PRESENCE of SEDIMENTATION to FILTRATION of STARCH SLURRY UNDER CONSTANT PRESSURE

ABSTRACTAn equation for predicting filtration flow rates in the presence of sedimentation at constant pressure drop was developed. It was applied to determine the average specific cake resistance infiltration of starch slurries at 18.8 to 115 kPa pressure drop range. At these conditions, corn, potato and sweet potato starch filter cakes were incompressible but wheat starch cake was compressible.

The Use of Multistage Centrifugal Pumps in Hydraulic-Lift Power Oil Systems

Introduction Amoco Production Co., as operator for the Chakachatna Group, erected four platforms in Cook Inlet, AK, during 1965-67. An early decline in producing rates and bottomhole pressures required producing rates and bottomhole pressures required us to use hydraulic lift systems in 1968. These systems have triplex pumps supplying power oil into a common header at 3,400 psig (23 400 kPa) discharge pressure. The pumps are driven by either 200-hp pressure. The pumps are driven by either 200-hp (152-kW) electric motors or 120- and 180-hp (90- and 140-kW) six-cylinder engines fueled by natural gas. Total platform hydraulics varies from 850 to 1,600 hp (635 to 1200 kW).Drilling programs, begun during 1976, required the platform lift systems to expand by about 700 hp (520 kW) on Platform Baker and 1,100 hp (820 kW) on Platform Anna. Alternatives for Lift Expansion We studied alternatives for expanding the artificial lift capacity of Platforms Anna and Baker. These included (1) additional triplex pumps similar to units already in service; (2) a turbine-driven, centrifugal pump package to operate in parallel with the existing pump package to operate in parallel with the existing triplex pumps; (3) electrically driven, submersible centrifugal pumps (ESP's) operating as high-pressure, power oil pumps in parallel with existing triplex pumps; and (4) ESP's conventionally installed downhole in new or existing wells. The initial investment and operating costs were lower for the turbine-driven, centrifugal pump package for Platform Anna and the electric submersible pumps Platform Anna and the electric submersible pumps operating as high-pressure, power oil pumps on Platform Baker. Platform Baker. The equipment installed on Platform Anna was an 1,100-hp (840-kW) 12-stage centrifugal pump driven by a gas turbine. This equipment is similar to that in waterflood service on Amoco's Cook Inlet platforms. Centrifugal pumps of this type are usually platforms. Centrifugal pumps of this type are usually available 98% of the time, which is a far better percentage than the positive-displacement pumps. percentage than the positive-displacement pumps. The equipment installed on Platform Baker comprised two 350-hp (270-kW) ESP's to pump power oil in parallel with the existing triplex pumps. power oil in parallel with the existing triplex pumps. Major considerations were the availability of electric power and the lack of adequate floor space for more power and the lack of adequate floor space for more conventional equipment. The ESP's were installed in empty platform well slots and arranged so that they could be serviced by platform cranes.Although economics was a major consideration when choosing to install centrifugal pumps as power oil pumps, other advantages included (1) reduced floor-space requirements, (2) reduced vibrations and noise, (3) reduced pulsation in the hydraulic system, and (4) reduced high-pressure piping requirements, as compared with the triplex pumps.Information obtained from a hydraulic pump manufacturer indicated that the power oil expansion on Platform Baker was the first time that power oil had been generated using ESP'S. However, a power water system does operate on the U.S. West Coast. Likewise, although turbine-driven, multistage centrifugal pumps are used as crude oil shipping pumps, the installation of this equipment on pumps, the installation of this equipment on Platform Anna for power oil service was unique. Platform Anna for power oil service was unique. System Design Details Design considerations unique to centrifugal pumps exist that must be considered when designing similar installations. Care was taken on Platform Baker to ensure operation of the ESP's at rates to prevent either upthrust or downthrust conditions. The 241-stage pump initially installed on Platform Baker was designed for 4,000 B/D (636 m /d) at 3,400 psi (23 400 kPa). Start-up occurs with the flow valve closed and the relief valve fully open (Fig. 1). The relief valve is sized for a 3,400 psig (23 400 kPa) pressure drop across the valve when opened. After a pressure drop across the valve when opened. After a set time (about 20 seconds) the relief valve closes and the flow valve opens. The pressure relief valve is set to open if the pressure reaches 3,650 psig (25 150 kPa). The flow valve acts as a backpressure valve to keep a minimum discharge pressure of 2,400 psig (16 550 kPa) on the pump. JPT P. 1196