Method of operating a heat pump dryer and heat pump dryer

Abstract

A heat pump dryer is provided which includes a process air circuit and a heat pump unit having a primary 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 refrigerant evaporator. At least one 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.

1 . A heat pump dryer comprising a process air circuit and a heat pump unit having a primary 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 refrigerant evaporator, wherein:
 at least one 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, 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.   
     
     
         2 . The heat pump dryer according to  claim 1 , 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.   
     
     
         3 . The heat pump dryer according to  claim 1 , 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.   
     
     
         4 . The heat pump dryer according to  claim 1 , wherein the waste heat generating component comprises at least one of: an electric device, an electronic device, a powered device, and a passive device. 
     
     
         5 . The heat pump dryer according to  claim 3 , wherein the waste heat generating component comprises at least one of: an electric motor, and at least one controller for varying the speed of an electric motor. 
     
     
         6 . The heat pump dryer according to  claim 5 , wherein the controller for varying the speed of an electric motor is an inverter. 
     
     
         7 . The heat pump dryer according to  claim 1 , wherein the auxiliary fan is adapted to suck in air from at least one of:
 inside the cabinet of the heat pump dryer, outside the cabinet of the heat pump dryer, a rear side of the heat pump dryer, a front side of the heat pump dryer, and a bottom side of the heat pump dryer.   
     
     
         8 . The heat pump dryer according to  claim 1 , wherein the auxiliary refrigerant evaporator is a dual mode auxiliary heat exchanger arranged outside the process air circuit and adapted to be operated in evaporator mode or in condenser mode. 
     
     
         9 . The heat pump dryer according to  claim 1 , 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. 
     
     
         10 . A method of operating a heat pump dryer, the heat pump dryer comprising a process air circuit, a heat pump unit having a primary 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 heat pump unit, and at least one auxiliary fan adapted to impinge an air stream at the auxiliary refrigerant evaporator, the method comprising the step of:
 operating and controlling the auxiliary fan so that ambient air heated up by heat released from said waste heat generating component is directed towards at the auxiliary evaporator, or   monitoring the temperature of the ambient air around the location where the auxiliary refrigerant evaporator is arranged and operating and controlling the auxiliary fan on the basis of the monitored temperature.   
     
     
         11 . The method of operating a heat pump dryer, according to  claim 10 , further comprising the step of:
 operating the waste heat generating component so as to heat up the ambient air around the location where the auxiliary refrigerant evaporator is arranged.   
     
     
         12 . The method according to  claim 10 , wherein the auxiliary fan is activated and deactivated according to at least one of:
 a temperature difference between refrigerant and air near or at the auxiliary refrigerant evaporator, the refrigerant temperature preferably being measured near or at the primary refrigerant evaporator,   an air temperature near or at at least one of: the auxiliary refrigerant evaporator, the auxiliary fan, and the waste heat generating component of the heat pump dryer,   at least one of: a temperature of the refrigerant, and a pressure of the refrigerant, both measured near or at a refrigerant outlet of the primary evaporator,   a temperature of refrigerant near or at at least one of: a refrigerant outlet and a refrigerant inlet of the auxiliary refrigerant evaporator,   a temperature difference between refrigerant and air near or at the auxiliary refrigerant evaporator, and   at least one of: a temperature of the process air, and humidity of the process air, both near or at a process air inlet of a drum of the heat pump tumble dryer.   
     
     
         13 . The method according to  claim 10 , wherein the auxiliary fan is activated if the temperature of the refrigerant near or at an outlet of the primary refrigerant evaporator near or at an inlet of the auxiliary evaporator is at least below a first preset temperature, and wherein the auxiliary 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. 
     
     
         14 . The method according to  claim 10 , wherein the 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 evaporator, and wherein the auxiliary 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. 
     
     
         15 . The heat pump dryer according to  claim 2 , 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.   
     
     
         16 . The heat pump dryer according to  claim 15 , wherein the waste heat generating component comprises at least one of: an electric device, an electronic device, a powered device, and a passive device. 
     
     
         17 . The heat pump dryer according to  claim 16 , wherein the waste heat generating component comprises at least one of: an electric motor, and at least one controller for varying the speed of an electric motor. 
     
     
         18 . The heat pump dryer according to  claim 17 , wherein the auxiliary fan is adapted to suck in air from at least one of: inside the cabinet of the heat pump dryer, outside the cabinet of the heat pump dryer, a rear side of the heat pump dryer, a front side of the heat pump dryer, and a bottom side of the heat pump dryer. 
     
     
         19 . The heat pump dryer according to  claim 16 , wherein the auxiliary refrigerant evaporator is a dual mode auxiliary heat exchanger arranged outside the process air circuit and adapted to be operated in evaporator mode or in condenser mode. 
     
     
         20 . The heat pump dryer according to  claim 16 , 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.