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Clathrate Glider – Matlab Trajectory Analysis Program

IP.com Disclosure Number: IPCOM000184119D
Publication Date: 2009-Jun-11
Document File: 3 page(s) / 68K

Publishing Venue

The IP.com Prior Art Database

Abstract

A program is disclosed that allows a user to determine a fairly accurate estimate of the trajectory of a clathrate glider as a function of its critical design parameters, such as glider volume and shape, heat transfer, total clathrate contained, ocean temperature and pressure, etc. The program analyzes these parameters and graphs an approximate trajectory based on iterations of these changing parameters during multiple dive cycles. The program contains sections that take in specific information relevant to the clathrate glider dive cycle. The first section takes in basic material and design information about the heat exchanger for the program to use in its heat transfer calculations. The section after this is an array of approximate water temperatures off the coast of California as a function of depth in increments of 25 m. The final section takes in basic information about the glider’s overall dimensions and desired trajectory, as well as specific clathrate data for the type of clathrate being used. The program is specific to a clathrate glider and is written to estimate the heat transfer for a conductive heat exchanger that transmits heat conductively between the ambient ocean water and clathrate solution (in the current design, via an aluminum finned exchanger). The type of clathrate, the size and shape of the glider, and the type of rigid heat exchanger are all up to the design and the program can be modified to easily function with new values for these parameters. The user would have to find and manually input his or her own temperature array to analyze the clathrate glider’s dive trajectory in another location other than the one given. The program will fail if the desired location does not have depths that allow the ocean water to reach the freezing temperature of the chosen clathrate solution. Program Functionality Overview The program functions using a simplified Runga Kutta type method, in which the glider’s position as a function of time is estimated in “time steps”, or increments of time, as opposed to instantaneously along the entire curve. As the glider sinks, the temperature around it is changing, so the heat transfer is never constant, so the program recalculates the clathrate temperature over each time step with new ocean water and clathrate temperatures. Once the glider reaches a depth that is suitable for freezing clathrate, the program switches over to a new section to begin estimating the amount of ice being formed. During phase, the program also recalculates the net buoyancy of the glider over each time step. The program continues calculating new ice production even when the glider reaches neutral buoyancy, and only stops once the glider has ascended past the depth at which ice is able to be made. During this period, the rate at which ice is formed is approximately constant, since there is almost no change between the temperate of ocean water at these depths (over 900 m). The program can be set up to calculate the ascent of the glider assuming no heat transfer (cut off heat exchanger) or normal heat transfer (heat exchanger runs continuously throughout dive cycle). This drastically affects both ascent time and time spent at the surface. The code treats this period as a black box, starting its second dive based on a constant, pre-programmed time at the surface (can be modified). The program is especially useful for data on the second dive, which can be extrapolated to match all subsequent dives. The maximum depth reached on the second dive is less than the first, because it is assumed that the clathrate will stay roughly around its freezing temperature for the vast majority of its dive cycle, meaning it will require less heat transfer to freeze the ice needed for buoyancy changes. However, ascent time will be slightly more, because the difference in density of the glider will be less (as it as created less ice). The program shows this data visually in its graph.

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Clathrate Glider - Matlab Trajectory Analysis Program

A program is disclosed that allows a user to determine a fairly accurate estimate of the trajectory of a clathrate glider as a function of its critical design parameters, such as glider volume and shape, heat transfer, total clathrate contained, ocean temperature and pressure, etc. The program analyzes these parameters and graphs an approximate trajectory based on iterations of these changing parameters during multiple dive cycles.

The program contains sections that take in specific information relevant to the clathrate glider dive cycle. The first section takes in basic material and design information about the heat exchanger for the program to use in its heat transfer calculations. The section after this is an array of approximate water temperatures off the coast of California as a function of depth in increments of 25 m. The final section takes in basic information about the glider's overall dimensions and desired trajectory, as well as specific clathrate data for the type of clathrate being used.

The program is specific to a clathrate glider and is written to estimate the heat transfer for a conductive heat exchanger that transmits heat conductively between the ambient ocean water and clathrate solution (in the current design, via an aluminum finned exchanger). The type of clathrate, the size and shape of the glider, and the type of rigid heat exchanger are all up to the design and the program can be modified to easily function with new values for these parameters. The user would have to find and manually input his or her own temperature array to analyze the clathrate glider's dive trajectory in another location other than the one given. The program will fail if the desired location does not have depths that allow the ocean water to reach the freezing temperature of the chosen clathrate solution.

Program Functionality Overview

The program functions using a simplified Runga Kutta type method, in which the glider's position as a function of time is...