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AmbFridge Ambulance Refrigeration System Arctic Ambulance Team Theresa Ring2, Stacy Tsang2, Jon Allison2


Tessa,,, 1Department

of Bioengineering, 2Department of Mechanical Engineering, Rice University, Houston, Texas

Mission Statement

The basis of the AmbFridge is a thermoelectric cooler (TEC). The How it works TEC uses the Peltier effect to cool one side while heating the other. •Thermoelectric cooler (TEC) uses the Peltier effectplate to cool The heat is then dissipated to the air by a copper spreader and a oneassembly. side while On heating the other heat sink/fan the other side of the TEC, a “cold sink” • “Cold sink” facilitates heat transfer from water to TEC transfers the coolness to a container of water. The water freezes at • Copper spreader plate and sink/fan assembly 0°C which is above the freezing pointheat of saline solution. Because we dissipate heat from water and generated fromcontroller TEC do not want the saline solution to freeze, a temperature will • Temperature supply to maintain then turn off the TEC. controller Once the regulates ice beginspower to melt, the TEC will turn proper temperature refrigerator back on and refreeze the waterofand continue to cycle off and on. The saline solutions are placed inside a dewar (a large vacuum How it is used insulated thermos). All of the other components will be contained in an acrylic assembly designed to be placed on top of, but not resting • Saline bags arebeplaced dewarfor (aaccess large vacuum on, the saline bags and easilyinside removable to the saline. insulated thermos) • Acrylic assembly holds all components of cooling This device is designed specifically for HFD but may easilysystem be • Allows for easy andfor quick assess to saline bags implemented (modifying as removal necessary) emergency response vehicles around the world Fig. 3. A cross section view of the AmbFridge showing the Fig. 3. A cross of section view ofdevice. the AmbFridge components the whole


Results of TEC Cooling System TEC Test - 12V, 3.5A; 600mL water


Transient Heating in a Room at 37 C 25 20 Temperature (C)

The AmbFridge Ambulance Refrigeration System must: The AmbFridge Ambulance Refrigeration System must: • Sustain the temperature of 2L of saline between •Sustain the temperature of 2L of saline between 0°C-1.1°C 0°C-1.1°C • Be a compact size no larger than 9”L x 10”W x 30”H Be a compact sizesaline no larger than 9”L without x 10”W power x 30”H • Maintain the cold temperature • Maintain cold saline temperature without power sources the for 4 hours during emergency medical services sources trainingfor 4 hours during emergency medical services • training Be compatible with 12V DC or 240V AC power source and • Be 12V DC or 240V AC power source and nocompatible more than with 15 amps more than 15 amps • no Meet ambulance safety requirements, including no toxic • Meet ambulance safety requirements, including no toxic substances or sharp objects (a fan guard is required) sharp objects (a fan guard is required) • substances Be operator or independent operatorenough independent • Be rugged to sustain daily ambulance activity • Be rugged to sustain surrounding daily ambulance activity (6/32—what is this)

Fig. 4. The cooling system of the Fig. 4.device Heat flow diagram for inside the cooling is supported an system. The cooling acrylic tube. system of the device is supported inside an acrylic tube.

showing the components of the whole device.

15 10 5

Temperature (C)

Develop a low-power refrigeration device to be used in Develop a low-power device to be used in emergency response refrigeration vehicles. emergency response vehicles. The AmbFridge refrigeration system is designed to hold up The AmbFridge refrigeration system for is designed to hold up to 2 liters of saline solution intended the administration to 2 liters of saline solution intended for the administration of therapeutic hypothermia. Therapeutic hypothermia is the of therapeutic hypothermia. most common recipients intentional cooling of the coreThe body temperature in order to of thisthe treatment, in which theThe coldmost saline is injected into the slow body’s metabolism. common recipients body, victims in of which heart attack and brainistrauma of this are treatment, the cold saline injectedOnce into the administered, therapeutic hypothermia increases body, are victims of heart attack and brain traumathe Once chance of surviving a heathypothermia attack by 14% and decreases administered, therapeutic increases the the likelihood of brain trauma by 16%. Early chance of surviving a heat attack by 14% andadministration decreases is critical for success this treatment. Therefore, once the likelihood of brainof trauma by 16%. Early installed in the ambulance, thesuccess AmbFridge allows administration is critical for of this treatment. emergency medical technicians (EMTs) to have cold saline Therefore, once installed in the ambulance, the AmbFridge available for immediate injection into the have cold allows emergency medical technicians (EMTs) saline available for immediate injection into the patient. Research has continued to show that early treatment is critical for has success. The Houston Department (HFD), Research continued to show Fire that early treatment is as well as for emergency services the United critical success. medical The Houston Firearound Department (HFD), as States, are looking medical to implement this around procedure need a well as emergency services the and United simple refrigeration system in which can keep States, are looking to implement thisthey procedure andthe need a saline solutions cool.system With 106 ambulances HFDthe and simple refrigeration in which they caninkeep 40,000solutions in the US, there is plenty of demand forinthe saline cool. With 106 ambulances HFD and AmbFridge Ambulance System.for the 40,000 in the US, thereRefrigeration is a large demand AmbFridge Ambulance Refrigeration System.

AmbFridge Design

0 0 -5 -10

40 35 30 25 20 15 10 5 0

Freezer Vacuum Dewar 0




40 6


80 10


Time (h)

Fig.1. A passive heating test was conducted inside a room at Time (hr) 37.1°C to determine theconducted heat flux into both a refrigerator and a to Fig.1. A cooling test was to measure the time required vacuum The temperature change was nearly four freeze 600dewar. mL of water using the AmbFridge. Data shows that the timesfroze slower inside the dewar. water after 7.5 hours.

Conclusion • Current design meets all requirements set by HFD however it may be modified to be implemented in any emergency response vehicle NEED: Simple able to cool saline to a low setting temperature and •• Next phase is todevice test the design in an ambulance temperature for uptotodevelop 4 hours.a cheaper alternative by selecting •maintain Future work may be done • SOLUTION: Thermoelectric cooler uses the Peltier effect to freeze a smaller, more efficient insulating container water in a highly insulated dewar. • Preliminary tests show that the AmbFridge has potential to be a Acknowledgements major improvement over current solution. The Arctic Ambulance Team would like to thank: Dr. David McStravick, Dr. Maria Oden, Dr. • Future work a TEC David Persse, Chiefcould Tommyentail Dowdy,designing Sr. Captain Don Gray,cooling Dr. Stephanie Kreml, Mr. Joe Gesenhues, Carlos Amaro, and the TECs Houstonto Fire Department.power Funding provided by the Rice SystemMr.with more efficient decrease consumption University Center for Civic Engagement, Department of Bioengineering and Department of in ambulance Mechanical Engineering.

References Acknowledgements Godfrey, Electronic Cooling: Thermoelectric Coolers. The ArcticSara. Ambulance Team would An likeIntroduction to thank: Dr.toDavid McStravick, Dr. Maria Oden, Dr. (Sept. 19, 2007) David Persse, Chief Tommy Dowdy, Sr. Captain Don Gray, Dr. Stephanie Kreml, Mr. Joe ElectronicsCooling Online Gesenhues, Mr. Carlos Amaro, the Houston Fire Department, and the Rice University Center for Newman, M. SCA Treatment. (Sept 25, 2007) Civic Engagement Sudden Cardiac Arrest Foundation.

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