Oviedo, FL, United States

Rini Technologies Inc

www.rinitech.com
Oviedo, FL, United States
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Bostanci H.,University of Central Florida | Bostanci H.,University of North Texas | Singh V.,University of Central Florida | Singh V.,Schlumberger | And 4 more authors.
ACS Applied Materials and Interfaces | Year: 2013

In this experimental study, two surface modification techniques were investigated for their effect on heat transfer enhancement. One of the methods employed the particle (grit) blasting to create microscale indentations, while the other used plasma spray coating to create microscale protrusions on Al 6061 (aluminum alloy 6061) samples. The test surfaces were characterized using scanning electron microscopy (SEM) and confocal scanning laser microscopy. Because of the surface modifications, the actual surface area was increased up to 2.8× compared to the projected base area, and the arithmetic mean roughness value (Ra) was determined to vary from 0.3 μm for the reference smooth surface to 19.5 μm for the modified surfaces. Selected samples with modified surfaces along with the reference smooth surface were then evaluated for their heat transfer performance in spray cooling tests. The cooling system had vapor-atomizing nozzles and used anhydrous ammonia as the coolant in order to achieve heat fluxes up to 500 W/cm2 representing a thermal management setting for high power systems. Experimental results showed that the microscale surface modifications enhanced heat transfer coefficients up to 76% at 500 W/cm2 compared to the smooth surface and demonstrated the benefits of these practical surface modification techniques to enhance two-phase heat transfer process. © 2013 American Chemical Society.


Bostanci H.,Rini Technologies Inc | Rini D.P.,Rini Technologies Inc | Kizito J.P.,North Carolina A&T State University | Singh V.,University of Central Florida | And 2 more authors.
International Journal of Heat and Mass Transfer | Year: 2012

A spray cooling study was conducted to investigate the effect of enhanced surfaces on Critical Heat Flux (CHF). Test surfaces involved micro-scale indentations and protrusions, macro (mm) scale pyramidal pin fins, and multi-scale structured surfaces, combining macro and micro-scale structures, along with a smooth surface that served as reference. Tests were conducted in a closed loop system using a vapor atomized spray nozzle with ammonia as the working fluid. Nominal flow rates were 1.6 ml/cm 2 s of liquid and 13.8 ml/cm 2 s of vapor, resulting in a pressure drop of 48 kPa. Results indicated that the multi-scale structured surface helped increase maximum heat flux limit by 18% over the reference smooth surface, to 910 W/cm 2 at nominal flow rate. During the additional CHF testing at higher flow rates, most heaters experienced failures before reaching CHF at heat fluxes above 950 W/cm 2. However, some enhanced surfaces can achieve CHF values of up to ≈1100 W/cm 2 with ≈67% spray cooling efficiency based on liquid usage. The results also shed some light on the current understanding of the spray cooling heat transfer mechanisms. Enhanced surfaces are found to be capable of retaining more liquid compared to a smooth surface, and efficiently spread the liquid film via capillary force within the structures. This important advantage delays the occurrence of dry patches at high heat fluxes, and leads to higher CHF. The present work demonstrated ammonia spray cooling as a unique alternative for challenging thermal management tasks that call for high heat flux removal while maintaining a low device temperature with a compact and efficient cooling scheme. © 2012 Elsevier Ltd. All rights reserved.


Bostanci H.,Rini Technologies Inc | Rini D.P.,Rini Technologies Inc | Kizito J.P.,North Carolina A&T State University | Singh V.,University of Central Florida | And 2 more authors.
International Journal of Heat and Mass Transfer | Year: 2014

An experimental spray cooling study was carried out to investigate the effect of enhanced surfaces on heat transfer performance. Test surfaces involved; (a) micro scale indentations and protrusions, (b) macro (mm) scale pyramidal, triangular, rectangular, and square pin fins, and (c) multi-scale structures that combine macro and micro scale structures, along with a smooth surface that served as reference. Tests were conducted in a closed loop system using vapor atomized spray nozzles with ammonia as the working fluid. Cooling performance data for each enhanced surface were obtained applying heat fluxes of up to 500 W/cm2, and using flow rates of 1.6 ml/cm2-s of liquid and 13.8 ml/cm2-s of vapor. Typical temperature readings with embedded thermocouples were verified using infrared thermography method. Data indicated that the multi-scale structured surface achieved the highest heat transfer coefficient (HTC) of 772,000 W/m2 °C, corresponding to 161% enhancement over the reference surface. The results suggest that the multi-scale structured surface can combine the unique benefits of the micro and macro scale structures, and provide some insights to the understanding of the spray cooling heat transfer mechanisms by emphasizing the importance of boiling through surface nucleation. Therefore ammonia spray cooling, with the utilization of enhanced surfaces, offers significant cooling performance for high heat flux thermal management applications that target to maintain low device temperatures with a compact and efficient cooling system. © 2014 Elsevier Ltd. All rights reserved.


Bostanci H.,Rini Technologies Inc | Van Ee D.,Rini Technologies Inc | Saarloos B.A.,Rini Technologies Inc | Rini D.P.,Rini Technologies Inc | Chow L.C.,University of Central Florida
IEEE Transactions on Components, Packaging and Manufacturing Technology | Year: 2012

A spray cooling system was developed and tested for thermal management of power inverter modules utilized in automotive applications. The system featured an array of 1 × 2 pressure atomized nozzles that used 88°C boiling point antifreeze coolant with 0.15-l/min.cm 2 liquid flow rate and 145-kPa pressure drop. A 2-cm 2 simulated device, having two kinds of enhanced spray surface with microscale structures, reached up to 400-W/cm 2 heat flux with as low as 14°C surface superheat. These experimental results demonstrated the capability of greatly reducing the overall thermal resistance of the inverter modules that are commonly cooled with single-phase convective systems. The long-term reliability of the spray cooling was assessed with 2000 h of testing time. Performance of the presented system proved the spray cooling of power electronics as an attractive option that enables high power densities while maintaining acceptable and uniform device temperatures. In addition, due to the use of high temperature coolant at low flow rates, the spray cooling offers a compact and efficient system design. © 2011-2012 IEEE.


Wu W.,University of Central Florida | Du J.H.,University of Central Florida | Lin Y.R.,University of Central Florida | Chow L.C.,University of Central Florida | And 3 more authors.
Journal of Heat Transfer | Year: 2011

This study investigates a V-shaped corrugated carbon foam heat sink for thermal management of electronics with forced air convection. Experiments were conducted to determine the heat sink performance in terms of heat transfer coefficient and pressure drop. The test section, with overall dimensions of 51 mm L×51 mm W×19 mm H, enabled up to 166 W of heat dissipation, and 3280 W/ m2 K and 2210 W/ m2 K heat transfer coefficients, based on log mean and air inlet temperatures, respectively, at 7.8 m/s air flow speed, and 1320 Pa pressure loss. Compared to a solid carbon foam, the V-shaped corrugated structure enhances the heat transfer, and at the same time reduces the flow resistance. Physical mechanisms underlying the observed phenomena are briefly explained. With benefits that potentially can reduce overall weight, volume, and cost of the air-cooled electronics, the present V-shaped corrugated carbon foam emerges as an alternative heat sink. © 2011 American Society of Mechanical Engineers.


Grant
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase II | Award Amount: 749.99K | Year: 2013

ABSTRACT: In the proposed Phase II program, RINI will demonstrate the key attributes of a thermal management (TM) concept for High Performance Electric Actuation System (HPEAS). The TM system does not interfere with the aircraft Environment Control System (ECS) nor the aircraft Power and Thermal Management System (PTMS). The concept is based on enhanced forced convection with autonomously controlled variable speed fans. It is expected this approach can address essentially all scenarios encountered in electrical actuation of flight control surfaces. The TM system can function in a wide range of environmental temperature and pressure, and under a variable gravity situation. In the Phase I, it was demonstrated that forced convection and radiation are sufficient to transport the waste heat from the HPEAS to the bay ambient air with temperatures defined in the solicitation. Key components of the Electro-Mechanical Actuation (EMA) hardware were kept below their respective operating temperature limits for all ambient conditions. In the Phase II program, TM systems will be designed, fabricated and applied to flight quality EMA hardware in collaboration with a prime aerospace company. BENEFIT: The primary benefit of the proposed technique is to greatly increase the heat transfer effectiveness from EMAs to ambient air under various flight conditions and body force. By significantly enhancing air circulation in bays, EMAs located there can operate at much higher power without overheating. It is anticipated the proposed TM system can find application in the cooling of electric motors and generators in hybrid and electric vehicles. The technology developed can also be applied to many types of portable systems such as personal cooling systems, etc.


Grant
Agency: Department of Defense | Branch: Special Operations Command | Program: SBIR | Phase: Phase II | Award Amount: 961.44K | Year: 2014

The Tactical Assault Light Operator Suit (TALOS) is being developed by the United States Special Operations Command (USSCOM). Warfighters operating in hot regions while wearing encapsulating Personal Protective Equipment (PPE) will require a Compact and Quiet Microclimate Cooling System (CQ-MCS) to protect the suit operators from heat stress. RINI Technologies has developed a 1 liter sized man-portable personal cooling product that keeps a soldier"s body cool. Personal cooling technology improves physical and cognitive function, and reduces dehydration; benefits that have a positive impact on health and mental readiness, mission endurance and operational readiness. The proposed Phase II effort will focus on integrating RINI"s personal cooling technology with the TALOS suit. In the 6 month base effort RINI will test and evaluate the noise characteristics of RINI"s cooling system and deliver (3) prototype systems and (3) integration kits for the Gen 1 TALOS suit. In the Option 1 effort, RINI will target a 20% system weight reduction and 50% noise reduction and investigate using TALOS physiological data to control the CQ-MCS cooling rate. RINI will fabricate, test and deliver (3) CQ-MCS prototypes with (3) Gen 2 integration kits at the conclusion of the Option 1 effort.


Grant
Agency: Department of Defense | Branch: Navy | Program: SBIR | Phase: Phase II | Award Amount: 748.14K | Year: 2010

The objective of this project is to prove the demonstrate prototype systems for heating and cooling a diver in the Shallow Water Combat Submersible (SWCS). Rini Technologies, Inc. has demonstrated the feasibility of a miniature heat pump and proposes to build complementary heating and cooling systems to provide thermal protection for both cold and warm water diving in contaminated water. Both units are capable of operation from a similarly size battery for greater than 2.6 hours but can be plugged into a power source of the SWCS for extended (>12 hours) run time. Each of the units proposed will be 8.5” long and less than 4” diameter. The heating system provides 300W of heat via 35°C water to the tube suit in 1.7°C ambient ocean water while consuming only 110W of electrical power. The cooling unit will provide 250W of cooling via 20°C water in 38°C ambient ocean water, consuming only 80W of electrical power. Through the use of these systems, the Navy can perform un-encumbered long duration dives in contaminated water at temperature extremes in the SWCS and allow for un-tethered diving.


Grant
Agency: Department of Defense | Branch: Navy | Program: SBIR | Phase: Phase II | Award Amount: 559.99K | Year: 2014

The objective of this project is to finish the development and qualification testing of Diver Heating and Cooling Systems. Both units are capable of operation from a similarly size battery for greater than 3 hours but can also be plugged into SDV boat power for very long durations. Each of the units proposed will be 8.5 long and less than 4 diameter. The heating system provides 300W of heat to the diver by pumping 38C water to the tube suit. The cooling unit will provide 250W of cooling to the diver by providing a flow of 20C water into the tube suit cooling garment.


Grant
Agency: Department of Defense | Branch: Air Force | Program: SBIR | Phase: Phase I | Award Amount: 149.93K | Year: 2012

ABSTRACT: In the proposed Phase I program, we will validate and optimize a thermal management (TM) concept for High Performance Electric Actuation System (HPEAS). The TM system does not interfere with the Environment Control System (ECS) nor the Power and Thermal Management System (PTMS). The concept is based on enhanced forced convection and thermal energy storage (TES). It is expected this approach can address essentially all scenarios encountered in electrical actuation of flight control surfaces. The TM system can function in a wide range of environmental temperature and pressure, and under a variable gravity situation. During most of the flight time, forced convection and radiation are sufficient to transport the waste heat from the HPEAS to the bay wall or wing skin for rejection to ambient air. Phase change material (PCM) will absorb heat during periods of peak power and/or when the ambient condition is not suitable for heat sinking. The feasibility and effectiveness of the proposed concept will be demonstrated by performing experiments with a full-scale lab prototype simulating an electromechanical actuator (EMA). The experimental data can also be used to validate a numerical model which is essential for design and optimization of TM systems. In the Phase II program, TM systems will be designed, fabricated and applied to flight quality EMA hardware in collaboration with a prime aerospace company. BENEFIT: The primary benefit of the proposed technique is to greatly increase the heat transfer effectiveness from EMAs to ambient air under various flight conditions and body force. By significantly enhancing air circulation in bays, EMAs located there can operate at much higher power without overheating. The numerical model developed in this program can be used to optimize heat removal by air surrounding complex-shaped heat sources. It is anticipated the proposed TM system can find application in the cooling of electric motors and generators in hybrid and electric vehicles. The technology developed can also be applied to many types of portable systems such as personal cooling systems, etc.

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