Determining temperature control of wash water in a laundry environment

Abstract

Fisher and Paykel (F&P) are developing a new model of washing machine. One of its key features will be that it uses less water. It is important to regulate the operating temperature of washing machines since if they operate hotter than the user-selected temperature there is a risk of damage to clothes and if they operate below the user-selected temperature there is a risk of incompletely dissolved detergent being sprayed onto clothes, which is also undesirable. F&P seek to improve their temperature regulation strategies from the current state-of-the-art. Further, since the new machine will have a smaller mass of water relative to clothes load, the impact of abnormal clothes loads and of start-up disturbances in water supply temperatures (e.g. cold slugs in hot water supply) on the bulk temperature is greater. Thus a thorough review of temperature regulation strategies is well motivated.