System and method for producing and determining cooling capacity of two-phase coolants

Abstract

The invention provides systems and devices for producing two-phase coolants such as an ice slurry. Also provided are methods for producing two-phase coolants, and methods for using the two-phase coolants to lower the temperature or maintain a low temperature in any subject, system, object, device, or application where particular low temperatures are desired. Also provided are systems for determining the cooling capacity of two-phase coolants.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority to U.S. Provisional Application No. 61 / 037,949, filed Mar. 19, 2008 and International Application No. PCT / US2008 / 080435, filed Oct. 20, 2008. The disclosure of each application is incorporated by reference herein, in its entirety and for all purposes.FIELD[0002]The invention relates generally to the field of refrigeration and cooling. More specifically, the invention relates to systems for producing a coolant such as a two-phase coolant and to systems for measuring the cooling capacity of coolants such as two-phase, liquid-solid coolants.BACKGROUND[0003]Numerous industries require cooling systems for a large variety of applications. In many cases, refrigerant chemicals or machines are used to generate cold air or ice for a desired application. Although various cooling systems have been proposed, there remains a need in the art for improved cooling systems.SUMMARY[0004]In one aspect, the invention provides ...

AI Technical Summary

Benefits of technology

"The invention provides systems and methods for producing a two-phase coolant, such as an ice slurry, using a microparticulate solid and a carrier fluid. The coolant can be used for inducing hypothermia in a subject, cooling perishable goods, and cooling devices. The system can also detect the solid void fraction and solid particle size in the coolant. The technical effects of the invention include improved cooling capacity, reduced solidification time, and improved stability of the coolant."

Problems solved by technology

In some aspects, the disturbing step comprises ultrasonically disturbing the stable flow.

Solidification of the fluid inside the nozzle can potentially cause clogging of the fluid flow space 56 of the nozzle or clogging of the apertures.

The high volume and pressure pumping of the two phase coolant, for example, out of a water cannon can be used to disperse rioting crowds through the creation of severe discomfort through the rapid cooling caused by full body exposure to the two phase coolant.

In extreme heat events, the heat can exceed the limits of the structural members, resulting in building collapse, space craft disintegration, or failure of mechanical systems.

But because many refrigerant chemicals such as chlorofluorocarbons are toxic and can potentially damage the environment, such cooling systems are less preferred than those embodiments described herein that can be operated without the use of refrigerant chemicals.

Similarly, because many commercial air conditioning or refrigeration units can use large amounts of energy, potentially taxing energy grids during peak demand, such cooling systems are less preferred than those embodiments described herein that can be operated without the use of large amounts of energy.

One obstacle to providing rapid cooling, for example, to induce therapeutic hypothermia in the field is finding a power source large enough to cool liquids such as a saline solution to form ice in the short time span that is available to treat a patient.

In addition, in the therapeutic setting, this power need is complicated by the fact that cooling of the patient ideally begins outside of the hospital, meaning that the large power source needs to be available on emergency vehicles.

Refrigeration units that provide that type of cooling power are available, but generally require special 220 volt wiring and are generally large and heavy, weighing hundreds of pounds.

Moreover, as conditions are often not ideal, it is likely that these estimated power needs represent a significant under-estimation of the actual power that would be required.

Thus, the requisite refrigeration units in reality are likely to be even heavier and require more power to operate.

The size and power requirement limitations would limit the ability to produce a two phase coolant in an emergent setting in a hospital building, and severely limit, if not prohibit the ability to produce such coolants from an emergency vehicle within the time constraints of a medical emergency.

Two phase coolants such as slurry lose their preferred ice particle shape and pumpability characteristics, however, upon storage, thereby reducing the therapeutic value of the coolant.

Over time, the dendritic nature of the ice crystals is restored and the slurry would no longer be able to be moved, even pumped, within the tight constraints of, for example, an intravenous tube.

However, such use of thermodynamic energy for cooling liquids creates temperatures below the eutectic point of salt water, which results in an ice slurry having a temperature much lower than 0° C., which could be harmful to a patient.

In addition, the cooling of the fluid can result in the freezing of fluid not in direct contact with the heat exchanger tube sidewalls.

One of the challenges of creating a coolant of this type is the propensity of the ice particles to aggregate and coalesce, ruining the pumpability of the slurry.

The shape of the formed ice can impede or even prevent transport pumping of the slurry through tubes, for example, for delivery to a patient.

In addition, heat transfer equations can be complicated by changing temperatures in the heat exchanger wall as a function of distance through the device.

Additionally, the collapse of the bubble under the pressure of the impinging jet may cause local fluctuations in the equilibrium freezing temperature leading to heterogeneous ice nucleation.

This local high pressure field can lead to a localized increased equilibrium freezing temperature which leads to ice nucleation.

In addition, in the post bubble collapse period, there is an area of relative negative pressure which also leads to a localized increase in equilibrium freezing temperature.

Regardless, secondary ice nucleation effects are not explained by the collapse of a cavitation bubble, as the time scales are too long.

For example, uncharacteristic changes in heat flow can cause the system to systematically evaluate temperature, rotation rate, and torque, individually and / or then in combination, to identify the cause of the system failure.

Thus, optimal ice slurry production can have a target heat transfer coefficient that, if not met, will indicate a failure in the system.

A change in the temperatures of the coolant and ice slurry product can result in a change of the heat transfer coefficient.

A change in the operation of ice removal can result in a change of the heat transfer coefficient.

Images