Optimizing probe structure for dual-probe seafloor heat flow meter

This paper alms to optimize the probe structure for dual-probe seafloor heat flow meter. Firstly, with a constructed finite element model for seafloor pulsing dual-probe, a series of temperature-time data, which are used as the "observed" data, can be obtained by giving different probe structures and thermal properties. Then, we calculated medium thermal conductivity and its corresponding maximum relative error (RE lambda-UL) by using Pulsed Finite Line Source (PFLS) model, and optimize the probe structure in which RE lambda-UL is minimized. Finally, we optimized dual-probe structure with the now available manufacture technique of seafloor heat flow probe. Our results show that: (1) under each distinct combination of probe heat pulse strength (q), temperature measurement error (Delta T-m) and probe length (L), there must be a best probe spacing (Best_r), at that position, RE lambda-UL is least; (2) Best_r can be accordingly increased with q increasing or Delta T-m decreasing; (3) when q,Delta T-m and probe radius (a) are given! there is a significant linear positive correlation between Best_r and L; (4) when a is 1.0 mm, q is from 628.0 similar to 1100.0 J . m(-1), Delta T-m is from 0.5 mK to 1.0 mK, and L is from 20.0 mm to 42. 0 mm, Best_r ranges from 18.0 mm to 30.0 mm. In this case, the maximum relative error in medium thermal conductivity is within 5.5%, meanwhile, it reaches the maximum measurement temperature within 6 minutes, which means that the temperature measurement just needs about 7 minutes to calculate medium thermal conductivity after the beginning of pulse heating, which is about 8 minutes shorter than that of the Lister-type heat flow meter.