# Numerical computation and experimental assessment of a pressure-retaining gas-tight sediment sampler

## TL;DR

This paper studies a gas-tight sediment sampler, analyzing how pressure is retained during recovery and validating the findings with experiments.

## Contribution

A new numerical model and experimental validation of pressure-retaining mechanisms in sediment samplers under high pressure.

## Key findings

- The pressure-retaining performance is influenced by seawater and nitrogen temperatures and descent velocity.
- Pre-charging pressure and recovery velocity significantly affect the sampler's pressure retention.
- The numerical model was validated through ultra-high-pressure experiments and sea trials.

## Abstract

The pressure of the recovered sample is intricately connected to seawater temperature, the recovery velocity, and the pressure of the pre-charged gas. To better understand the sample pressure dynamics during the sampling recovery process, we focus on a gas-tight sediment sampler, delving into its pressure-compensation and pressure-retaining mechanisms. A comprehensive thermal and thermodynamic analysis is conducted throughout the entire pressure-retaining sampling process, examining the temporal variations in the temperatures of seawater and nitrogen within the sampler at various descending velocities. The heat transfer and thermodynamics are examined throughout the entire pressure-retaining sampling process to determine how changes in the temperatures of seawater and nitrogen, as well as the descent velocity, affect the pressure-retaining performance. The influence of pre-charging pressure and recovery velocities on the pressure-retaining performance of the sampler is examined. Then the proposed numerical model was well verified by the ultra-high-pressure vessel experiments of the sampler under 115 MPa. Finally, the sea trial results further verified the accuracy of the numerical model.