Laundry Treatment Apparatus Having Heat Pump System

Abstract

A laundry treatment apparatus, in particular a dryer or a washing machine having dryer function, comprises a storing compartment for storing laundry therein, in particular a rotatable drum, an air circulation channel connected at a first end and at a second end to the storing compartment, a blower for blowing the air through the air circulation channel and the storing compartment, a heat pump system having an evaporator and a condenser arranged in the air circulation channel, and a steam generator arranged within the body of the laundry treatment apparatus. A method of operating the laundry treatment apparatus comprises supplying steam generated by the steam generator into the air circulation channel and / or the storing compartment, and at the same time at least for an overlapping period, operating the heat pump system.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims priority to European Application No. 10163744.5, filed on May 25, 2010BACKGROUND OF THE INVENTION[0002]The invention relates to a laundry treatment apparatus having a heat pump system, and a method for operating the same. The laundry treatment apparatus may be a dryer or a washing machine having drying function.[0003]If a heat pump system is not operated permanently as in a freezer or refrigerator, but it is operated temporarily when momentarily required, the heat transfer capability for transferring heat from the evaporator to the condenser is slowly increasing over time after starting the heat pump system. It is known to use such heat pump systems in condenser dryers. There are different conventional approaches to increase the initial heat transfer capability and / or to reduce the time required till full heat transfer capability.[0004]For the dryer with heat pump system of DE 31 13 471 A1 it is proposed to heat the...

AI Technical Summary

Benefits of technology

[0010]It is an object of the invention to provide a laundry treatment apparatus having a heat pump system and a method of operating a laundry treatment apparatus, in which the time for the heat pump system to come to an elevated efficiency is shortened without the need for additional elements.

[0016]In an embodiment the steam is generated by the steam generator and supplied to the air circulation channel and / or the storing compartment for a predefined period since or after starting the operation of the heat pump system and then after the predefined period the steam generation and supply is stopped. By this overlap of the operation of the heat pump system and the steam generator the intermediate effect of additional energy consumption by the steam generator is limited and in total the result of this additional energy consumption and humidification of the laundry is more than counterbalanced by the acceleration of the equilibration process for the heat pump system to come to high efficiency in the drying cycle.

[0021]Alternatively or additionally one or more of the parameters are the pressure and / or temperature of the working fluid in the evaporator (for example measured at the inlet / outlet thereof), the condenser and / or the compressor. For example, the pressure within the evaporator is measured which indicates the pressure of the working fluid (or cooling fluid), wherein a sufficient pressure limit has to be achieved before the compressor and thus the heat pump system can operate efficiently.

[0031]According to a preferred embodiment the control unit of the laundry treatment apparatus is adapted to operate the heat pump system and the steam generator at the same time at least for one or a plurality of overlapping periods, preferably during the initial phase of the operation of the heat pump system such that the evaporator is heated in the start-up phase of the heat pump system. Thereby the working temperature of the evaporator and the coolant liquid therein is increased to increase the evaporation of the coolant liquid within the evaporator. This increases the efficiency of the compressor by providing coolant liquid vapour to be compressed.

[0034]According to an embodiment, the laundry treatment apparatus has a storing compartment, in particular a rotatable drum, that is enclosed by a tub or container and a sump arranged in the tub below the storing compartment (e.g. rotatable drum). A heating element arranged in or at the sump is configured to heat up water contained in the sump to generate steam and to supply it to the storing compartment. Preferably, the storing compartment has a plurality of openings connecting its interior and the outer volume within the tub, so that the steam can permeate into the storing compartment for laundry processing.

[0035]According to a preferred embodiment the blower has an operation mode with reduced or zero air conveying power. For example, an operation mode in which the blower is de-energized or stopped or in which the power provided to the blower is reduced. Then the control unit of the treatment apparatus is adapted to control the steam generator to generate and supply steam while the blower is de-energized or operating with a reduced air amount conveying power at least partially during the initial phase of operating the heat pump system. In case of reduced air conveying, the hot steam is first provided to the evaporator to heat up the evaporator and the reduced air circulation speed causes the heat exchange time (dwell time) between steam and evaporator to be extended. In case of de-energizing the blower the steam can diffuse to the evaporator and deposit the heat energy there. In particular, when the evaporator is arranged at an upper level within the body of the treatment apparatus, the hot steam will ascend and collect at the evaporator to heat it up. This chimney effect is improved when the laundry treatment apparatus is configured such that the evaporator is arranged above an inlet area or steam generation area for supplying the steam into the storing compartment and / or air circulation channel.

Problems solved by technology

By this overlap of the operation of the heat pump system and the steam generator the intermediate effect of additional energy consumption by the steam generator is limited and in total the result of this additional energy consumption and humidification of the laundry is more than counterbalanced by the acceleration of the equilibration process for the heat pump system to come to high efficiency in the drying cycle.

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