Method of operating a heat pump dryer and heat pump dryer

Abstract

Method of operating a heat pump dryer, the heat pump tumble dryer including a process air circuit and a heat pump unit having a refrigerant evaporator for cooling process air, a primary refrigerant condenser for heating process air, an auxiliary refrigerant evaporator arranged outside the process air circuit and connected between the primary refrigerant evaporator and a compressor of the heat pump unit, and at least one auxiliary fan adapted to impinge an air stream at the auxiliary heat exchanger. The at least one auxiliary fan is activated and deactivated by a control unit according to at least one of a temperature of the refrigerant and/or a pressure of the refrigerant, both preferably measured near or at a refrigerant outlet of the primary evaporator, a temperature of refrigerant near or at an refrigerant outlet or inlet of the auxiliary refrigerant evaporator, a temperature of the air near or at the auxiliary refrigerant evaporator, a temperature difference between refrigerant and air near or at the auxiliary refrigerant evaporator and, a temperature of the process air and/or humidity of the process air, both preferably near or at a process air inlet of a drying chamber of the heat pump tumble dryer.

1 . Method of operating a heat pump dryer, the heat pump dryer comprising a process air circuit and a heat pump unit having a refrigerant evaporator for cooling process air, a primary refrigerant condenser for heating process air, an auxiliary refrigerant evaporator arranged outside the process air circuit and connected between the primary refrigerant evaporator and a compressor of the heat pump unit, and at least one auxiliary fan adapted to impinge an air stream at the auxiliary heat exchanger, wherein the at least one auxiliary fan is activated and deactivated by a control unit according to at least one of:
 a temperature of the refrigerant and/or a pressure of the refrigerant, both preferably measured near or at a refrigerant outlet of the primary evaporator,   a temperature of refrigerant near or at an refrigerant outlet or inlet of the auxiliary refrigerant evaporator,   a temperature of the air near or at the auxiliary refrigerant evaporator,   a temperature difference between refrigerant and air near or at the auxiliary refrigerant evaporator, and   a temperature of the process air and/or humidity of the process air, both preferably near or at a process air inlet of a drying chamber of the heat pump tumble dryer.   
     
     
         2 . Method according to  claim 1 , wherein the at least one auxiliary fan is activated and deactivated according to:
 a temperature difference between refrigerant and air near or at the auxiliary refrigerant evaporator, the refrigerant temperature being measured at the inlet or outlet of the primary refrigerant evaporator or at the inlet or outlet of the auxiliary refrigerant evaporator.   
     
     
         3 . Method according to  claim 1 , wherein respective temperature and pressure values used by the control unit are measured by at least one of a temperature sensor, humidity sensor and pressure sensor, respectively, of the heat pump dryer. 
     
     
         4 . Method according to  claim 1 , wherein at least one of the at least one auxiliary fan is activated if the temperature of the refrigerant near or at an outlet of the primary refrigerant evaporator or near or at an inlet of the auxiliary heat exchanger is at least below a first preset temperature, and wherein the at least one fan is deactivated if the temperature of the refrigerant near or at an outlet of the primary refrigerant evaporator or near or at an inlet of the auxiliary heat exchanger is at least above the first preset temperature. 
     
     
         5 . Method according to  claim 1 , wherein at least one of the at least one auxiliary fan is activated if the temperature of the respective fan air stream is at least above the temperature of the refrigerant at the refrigerant outlet of the primary refrigerant evaporator or inlet of the auxiliary heat exchanger, and wherein the at least one fan is deactivated if the temperature of the fan air stream is at least below the temperature of the refrigerant at the refrigerant outlet of the primary refrigerant evaporator. 
     
     
         6 . Method according to  claim 1 , wherein the auxiliary refrigerant evaporator is a dual mode auxiliary heat exchanger arranged outside the process air circuit and operated in refrigerant evaporator mode, said dual mode auxiliary heat exchanger being adapted to be operated in refrigerant condenser mode. 
     
     
         7 . Method according to  claim 1 , wherein ambient air heated up by heat released from a waste heat generating components of the heat pump dryer is impinged at the auxiliary refrigerant evaporator. 
     
     
         8 . Heat pump dryer comprising a process air circuit and a primary heat pump unit having a primary refrigerant evaporator for cooling process air a primary refrigerant condenser for heating process air, an auxiliary refrigerant evaporator, connected between the primary refrigerant evaporator and a compressor of the heat pump unit, and at least one auxiliary fan adapted to impinge an air stream at the auxiliary refrigerant evaporator, further comprising a control unit adapted and designed for operating the heat pump dryer according to a method of  claim 1 . 
     
     
         9 . Heat pump dryer according to  claim 8 , wherein at least a waste heat generating component of the heat pump dryer, the auxiliary refrigerant evaporator and the auxiliary fan are mutually arranged so that the auxiliary fan is adapted to impinge ambient air heated up by heat released from said waste heat generating component at the auxiliary evaporator, and/or
 at least a temperature sensor is arranged outside the process air circuit and provided for detecting the temperature of the ambient air around the location where the auxiliary refrigerant evaporator is arranged.   
     
     
         10 . Heat pump dryer according to  claim 9 , wherein the mutual arrangement of the auxiliary refrigerant evaporator, the auxiliary fan and the waste heat generating component of the heat pump dryer with respect to the air stream an auxiliary fan airflow is at least one of:
 the auxiliary fan, auxiliary refrigerant evaporator and waste heat generating component are arranged in series,   the auxiliary fan is arranged between the waste heat generating component and the auxiliary refrigerant evaporator,   the auxiliary refrigerant evaporator is arranged between the waste heat generating component and the auxiliary fan,   the auxiliary fan, auxiliary refrigerant evaporator and waste heat generating component are substantially aligned with respect to the air stream generated by the auxiliary fan, and   the auxiliary fan, auxiliary refrigerant evaporator and waste heat generating component are substantially arranged along the direction of the air stream generated by the auxiliary fan.   
     
     
         11 . Heat pump dryer according to  claim 9 , wherein the temperature sensor is arranged at least one of:
 near or at the auxiliary refrigerant evaporator,   near or at the auxiliary fan,   between the auxiliary refrigerant evaporator and the auxiliary fan,   between the waste heat generating component of the heat pump dryer, and the auxiliary fan, and   between the waste heat generating component of the heat pump dryer and the auxiliary refrigerant evaporator.   
     
     
         12 . Heat pump dryer according to  claim 9 , wherein the waste heat generating component comprises an electric device and/or and electronic device and/or a powered device and/or a passive device. 
     
     
         13 . Heat pump dryer according to  claim 12 , wherein the waste heat generating component comprises at least one electric motor and/or at least one controller for varying the speed of an electric motor, preferably an inverter. 
     
     
         14 . Heat pump dryer according to  claim 8 , wherein the auxiliary refrigerant evaporator is an auxiliary dual mode heat exchanger arranged outside the process air circuit and operable in refrigerant evaporator mode or in refrigerant condenser mode. 
     
     
         15 . Heat pump dryer according to  claim 8 , further comprising an auxiliary refrigerant condenser arranged outside the process air and connected between the primary refrigerant condenser and refrigerant expansion means of the heat pump unit. 
     
     
         16 . Method according to  claim 2 , wherein respective temperature and pressure values used by the control unit are measured by at least one of a temperature sensor, humidity sensor and pressure sensor, respectively, of the heat pump dryer. 
     
     
         17 . Method according to  claim 2 , wherein at least one of the at least one auxiliary fan is activated if the temperature of the refrigerant near or at an outlet of the primary refrigerant evaporator or near or at an inlet of the auxiliary heat exchanger is at least below a first preset temperature, and wherein the at least one fan is deactivated if the temperature of the refrigerant near or at an outlet of the primary refrigerant evaporator or near or at an inlet of the auxiliary heat exchanger is at least above the first preset temperature. 
     
     
         18 . Method according to  claim 3 , wherein at least one of the at least one auxiliary fan is activated if the temperature of the refrigerant near or at an outlet of the primary refrigerant evaporator or near or at an inlet of the auxiliary heat exchanger is at least below a first preset temperature, and wherein the at least one fan is deactivated if the temperature of the refrigerant near or at an outlet of the primary refrigerant evaporator or near or at an inlet of the auxiliary heat exchanger is at least above the first preset temperature. 
     
     
         19 . Method according to  claim 2 , wherein at least one of the at least one auxiliary fan is activated if the temperature of the respective fan air stream is at least above the temperature of the refrigerant at the refrigerant outlet of the primary refrigerant evaporator or inlet of the auxiliary heat exchanger, and wherein the at least one fan is deactivated if the temperature of the fan air stream is at least below the temperature of the refrigerant at the refrigerant outlet of the primary refrigerant evaporator. 
     
     
         20 . Method according to  claim 3 , wherein at least one of the at least one auxiliary fan is activated if the temperature of the respective fan air stream is at least above the temperature of the refrigerant at the refrigerant outlet of the primary refrigerant evaporator or inlet of the auxiliary heat exchanger, and wherein the at least one fan is deactivated if the temperature of the fan air stream is at least below the temperature of the refrigerant at the refrigerant outlet of the primary refrigerant evaporator.