Hybrid Recirculating/Vented Tumble Dryer With Purposeful Fresh Air Inlet At Drying Chamber

Abstract

A hybrid vented tumble dryer which includes a drying chamber such as a rotatable drum, a heater, a process air fan, a recirculation duct, and a process air circuit configured to recirculate process air through the dryer. The dryer may include first and second drum seal gaskets located between the drum and first and second bulkheads, respectively. In some embodiments, the recirculation duct is in closed fluid communication with the heater. In other embodiments, the process air circuit is configured such that substantially the only fresh air which enters the process air circuit enters directly into the drying chamber prior to passing through the heater, or such that substantially the only fresh air which enters the process air circuit enters the process air circuit, in an airflow direction of the process air moving through the process air circuit, after the heater and before an outlet of the drying chamber.

We claim: 
     
         1 . A hybrid vented tumble dryer comprising:
 a drying chamber;   a heater configured to heat process air entering the drying chamber;   a process air fan configured to draw the process air through the drying chamber;   an exhaust duct configured to exhaust a first portion of the process air from the drying chamber;   a recirculation duct configured to direct a second portion of the process air from the drying chamber to the heater; and   a process air circuit configured to recirculate the process air through the hybrid vented tumble dryer and defined at least in part by the drying chamber, the heater, the process air fan, and the recirculation duct, wherein the process air circuit is configured such that:
 the drying chamber is located between the heater and the process air fan such that the process air leaving the heater passes through the drying chamber before the process air reaches the process air fan, 
 the recirculation duct is located between the process air fan and the heater such that the second portion of the process air leaving the process air fan passes through the recirculation duct before the process air reaches the heater, and 
 substantially the only fresh air which enters the process air circuit enters directly into the drying chamber prior to passing through the heater. 
   
     
     
         2 . The hybrid vented tumble dryer of  claim 1 , further comprising at least one gasket, wherein substantially the only fresh air which enters the process air circuit enters directly into the drying chamber at the at least one gasket. 
     
     
         3 . The hybrid vented tumble dryer of  claim 2 , wherein the drying chamber is a rotatable drum configured to rotate with respect to a bulkhead of the hybrid vented tumble dryer, and wherein the gasket is located between the rotatable drum and the bulkhead. 
     
     
         4 . The hybrid vented tumble dryer of  claim 3 , wherein the gasket includes at least one of: polyester, wool, polyurethane, ethylene propylene diene monomer rubber, and polytetrafluoroethylene. 
     
     
         5 . The hybrid vented tumble dryer of  claim 1 , further comprising a recirculation air filter removably mounted in the recirculation duct and configured to filter the second portion of the process air. 
     
     
         6 . The hybrid vented tumble dryer of  claim 5 , wherein the recirculation air filter is removably accessible from an inside of the drying chamber. 
     
     
         7 . A hybrid vented tumble dryer comprising:
 a drying chamber including an inlet and an outlet, wherein process air moving through the drying chamber enters at the inlet and exits at the outlet;   a heater configured to heat the process air entering the drying chamber;   a process air fan configured to draw the process air through the drying chamber;   an exhaust duct configured to exhaust a first portion of the process air from the drying chamber;   a recirculation duct configured to direct a second portion of the process air from the drying chamber to the heater; and   a process air circuit configured to recirculate the process air through the hybrid vented tumble dryer and defined at least in part by the drying chamber, the heater, the process air fan, and the recirculation duct, wherein the process air circuit is configured such that:
 the drying chamber is located between the heater and the process air fan such that the process air leaving the heater passes through the drying chamber before the process air reaches the process air fan, 
 the recirculation duct is located between the process air fan and the heater such that the second portion of the process air leaving the process air fan passes through the recirculation duct before the process air reaches the heater, and 
 substantially the only fresh air which enters the process air circuit enters the process air circuit, in an airflow direction of the process air moving through the process air circuit, after the heater and before the outlet of the drying chamber. 
   
     
     
         8 . The hybrid vented tumble dryer of  claim 7 , further comprising at least one gasket, wherein substantially the only fresh air which enters the process air circuit enters directly into the drying chamber at the at least one gasket. 
     
     
         9 . The hybrid vented tumble dryer of  claim 8 , wherein the drying chamber is a rotatable drum configured to rotate with respect to a bulkhead of the hybrid vented tumble dryer, and wherein the gasket is located between the rotatable drum and the bulkhead. 
     
     
         10 . The hybrid vented tumble dryer of  claim 9 , wherein the gasket includes at least one of: polyester, wool, polyurethane, ethylene propylene diene monomer rubber, and polytetrafluoroethylene. 
     
     
         11 . The hybrid vented tumble dryer of  claim 7 , further comprising a recirculation air filter removably mounted in the recirculation duct and configured to filter the second portion of the process air. 
     
     
         12 . The hybrid vented tumble dryer of  claim 11 , wherein the recirculation air filter is removably accessible from an inside of the drying chamber. 
     
     
         13 . A hybrid vented tumble dryer comprising:
 a rotatable drum;   a heater configured to heat process air entering the rotatable drum;   a process air fan configured to draw the process air through the rotatable drum;   an exhaust duct configured to exhaust a first portion of the process air from the rotatable drum;   a recirculation duct configured to direct a second portion of the process air from the rotatable drum to the heater;   a first bulkhead;   a first drum seal gasket located between the rotatable drum and the first bulkhead in a non-airtight manner such that fresh air can enter the rotatable drum at the first drum seal gasket;   a second bulkhead;   a second drum seal gasket located between the rotatable drum and the second bulkhead in the non-airtight manner such that the fresh air can enter the rotatable drum at the second drum seal gasket; and   a process air circuit configured to recirculate the process air through the hybrid vented tumble dryer defined at least in part by the rotatable drum, the heater, the process air fan, the recirculation duct, the first bulkhead, and the second bulkhead,   wherein the recirculation duct is in closed fluid communication with the heater.   
     
     
         14 . The hybrid vented tumble dryer of  claim 13 , wherein substantially the only fresh air which enters the process air circuit is the fresh air entering the rotatable drum at the first drum seal gasket and the second drum seal gasket. 
     
     
         15 . The hybrid vented tumble dryer of  claim 13 , wherein the fresh air enters the rotatable drum via a first airflow spacing provided between the first drum seal gasket and the first bulkhead, and via a second air airflow spacing provided between the second drum seal gasket and the second bulkhead. 
     
     
         16 . The hybrid vented tumble dryer of  claim 13 , wherein the fresh air enters the rotatable drum via a first airflow spacing provided between the first drum seal gasket and the rotatable drum, and via a second air airflow spacing provided between the second drum seal gasket and the rotatable drum. 
     
     
         17 . The hybrid vented tumble dryer of  claim 13 , wherein the first drum seal gasket and the second drum seal gasket are air-permeable, and wherein the fresh air enters the rotatable drum though the first drum seal gasket and the second drum seal gasket. 
     
     
         18 . The hybrid vented tumble dryer of  claim 13 , wherein the first drum seal gasket and the second drum seal gasket include at least one of: polyester, wool, polyurethane, ethylene propylene diene monomer rubber, and polytetrafluoroethylene. 
     
     
         19 . The hybrid vented tumble dryer of  claim 13 , further comprising a recirculation air filter removably mounted in the recirculation duct and configured to filter the second portion of the process air. 
     
     
         20 . The hybrid vented tumble dryer of  claim 19 , wherein the recirculation air filter is removably accessible at an access opening of the first bulkhead.