Curvilinear melting – A preliminary experimental and numerical study

Schüller, K.; Kowalski, Julia; Råback, Peter

doi:10.1016/j.ijheatmasstransfer.2015.09.046

Cited by 23 publications

(16 citation statements)

References 19 publications

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“…For instance, there are studies about the use of heating plates. One [11] deals with the application of an asymmetrically distributed force, another [12] presents a framework around differential heating and a constant contact force. By applying a temperature gradient at the surface of a pressurized plate, a curvilinear melting path can be enforced, which can be described by the curve radius and the mean velocity.…”

Section: A Melting Probesmentioning

confidence: 99%

Optimization Strategies for Real-Time Control of an Autonomous Melting Probe

Meerpohl

Flabkamp

Büskens

2018

2018 Annual American Control Conference (ACC)

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We present an optimization-based approach for trajectory planning and control of a maneuverable melting probe with a high number of binary control variables. The dynamics of the system are modeled by a set of ordinary differential equations with a priori knowledge of system parameters of the melting process. The original planning problem is handled as an optimal control problem. Then, optimal control is used for reference trajectory planning as well as in an MPC-like algorithm. Finally, to determine binary control variables, a MINLP fitting approach is presented. The proposed strategy has recently been tested during experiments on the Langenferner glacier. The data obtained is used for model improvement by means of automated parameter identification.

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Section: A Melting Probesmentioning

confidence: 99%

Optimization Strategies for Real-Time Control of an Autonomous Melting Probe

Meerpohl

Flabkamp

Büskens

2018

2018 Annual American Control Conference (ACC)

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“…The melting velocity W is the relative velocity between the heat source and the PCM. For straight melting it is constant and for curvilinear melting, it varies along the working surface Γ w as it is described in [23]. The boundary conditions for the pressure and temperature fields depend on the geometry, and are given by n=1:…”

Section: Mathematical Modelmentioning

confidence: 99%

“…The general approach follows [23] that first considered rotational melting modes. First, we assume that the exerted force is located at the center (r = 0) of the heat source and acts normal to the working surface.…”

Section: Curvilinear Close-contact Meltingmentioning

confidence: 99%

“…for exploring the Saturnian moon Enceladus [15], have been proposed. In contrast to the rather sophisticated hardware concepts that have been developed and tested in recent years [16], only minor steps have been undergone to model the process [23,1,24,9]. In this study, we will concentrate on the close-contact melting processes in the vicinity of a robotic melting probe, as they are key to modeling the macro-scale dynamics of the probe.…”

Section: Introductionmentioning

confidence: 99%

“…The results show consistently that in these cases the melting velocity W scales with the contact force F eff according to W ∼ F 1/4 eff . Recently, these results have been generalized to allow for rotational melting induced by an asymmetric surface temperature profile [23]. Characteristic to the temperature driven close-contact melting process is that the melt film thickness asymptotically tends to zero for increasing contact forces.…”

Section: Introductionmentioning

confidence: 99%

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Spatially varying heat flux driven close-contact melting – A Lagrangian approach

Schüller

Kowalski

2017

International Journal of Heat and Mass Transfer

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Close-contact melting refers to the process of a heat source melting its way into a phase-change material. Of special interest is the close-contact melting velocity, or more specifically the relative velocity between the heat source and the phase-change material. In this work, we present a novel numerical approach to simulate quasi-steady, heat flux driven close-contact melting. It extends existing approaches found in the literature, and, for the first time, allows to study the impact of a spatially varying heat flux distribution. We will start by deriving the governing equations in a Lagrangian reference frame fixed to the heat source. Exploiting the narrowness of the melt film enables us to reduce the momentum balance to the Reynolds equation, which is coupled to the energy balance via the velocity field. We particularize our derivation for two simple, yet technically relevant geometries, namely a 3d circular disc and a 2d planar heat source. An iterative solution procedure for the coupled system is described in detail and discussed on the basis of a convergence study. Furthermore, we present an extension to allow for rotational melting modes. Various test cases demonstrate the proficiency of our method. In particular, we will utilize the method to assess the efficiency of the close-contact melting process and to quantify the model error introduced if convective losses are neglected. Finally, we will draw conclusions and present an outlook to future work.

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