Author(s)

R. W. van Gils, M. F. M. Speetjens & H. Nijmeijer

Abstract

In this paper the feedback stabilisation of a two-dimensional pool-boiling system is discussed. The pool-boiling system is modelled by a so-called heater-only model, which consists of a Partial Differential Equation (PDE) which describes the heaters internal temperature field and its (nonlinear) boundary conditions given by the heat exchange between fluid and heater at the top and the heat supply at the bottom of the heater. The pool-boiling system is extended with an adjustable heat supply at the bottom of the heater, by which the unstable transition boiling regime is to be stabilised. Thereto, a feedback law, based on the Chebyshev-Fourier-cosine modes of the spectral discretisation of the temperature profile inside the heater, is applied to the system. The control parameters of this feedback law are designed such that satisfactory closed-loop dynamics are obtained. Using this specific feedback law, the control strategy is tested by simulations of the closed-loop pool-boiling system. Keywords: boiling, feedback, stabilisation, modal control, transition boiling, pool boiling, numerical simulation. 1 Introduction Pool boiling may serve as physical model for cooling applications using boiling heat transfer. Boiling heat transfer is emerging as novel cooling technique, since it affords cooling capacities substantially beyond that of convential methods, which are based on air-cooling and single phase liquid cooling, see Mudawar [1], Khan et al [2] and Brooks et al [3]. Therefore, controlling the dynamical behaviour of pool boiling systems is the principal subject of investigations in this study. A pool-boiling system is typically a system where a heater surface is submerged in a pool of saturated liquid. The heater surface is the fluid-heater interface where

Keywords

boiling, feedback, stabilisation, modal control, transition boiling, pool boiling, numerical simulation