Falling film evaporator having two-phase distribution system

Apparatus for distributing a two-phase refrigerant within a falling film evaporator comprising:

• an inlet, said two-phase refrigerant mixture being received into said distributor through said inlet;
• a first stage distributor portion, said first stage distributor portion receiving said two-phase refrigerant mixture from said inlet and defining a flow path for said two-phase refrigerant mixture which it generally oriented in a first flow direction and which maintains the velocity of the flow of said refrigerant therethrough generally constant;
• and
• a second stage distributor portion, said second stage distributor portion receiving said two-phase refrigerant mixture from said first stage distributor portion and defining a flow path for refrigerant which is generally oriented in a direction different from said first flow direction.

A refrigerant distributor comprising:

• an inlet;
• a cover, said cover defining a first plurality of holes generally along the length thereof;
• a first stage distributor section, said first stage distributor section being in flow communication with said inlet and defining, in cooperation with said cover, a first flow path of decreasing cross-sectional area in a downstream flow direction, said first flow path being in flow communication with said first plurality of holes defined by said cover;
• a second stage distributor plate, said second stage distributor plate disposed below said first stage distributor section;
• an injection plate, said injection plate defining a second plurality of holes, said injection plate and said second stage distributor plate cooperating to define a second flow path, downstream of said first flow path, said second stage injection plate defining a second plurality of holes, both said first plurality of holes and said second plurality of holes being in flow communication with said second flow path;
• and
• a bottom plate, said bottom plate defining a plurality of apertures, said bottom plate cooperating with said injection plate to define a distribution volume internal of said distributor, said distribution volume being in flow communication with both said plurality of apertures and with said second plurality of holes.

A falling film evaporator for use in a refrigeration chiller system comprising:

• a shell into which a two-phase mixture of refrigerant is received;
• a tube bundle disposed in said shell;
• and
• a refrigerant distributor disposed in said shell and overlying said tube bundle so that liquid refrigerant expressed out of said distributor is deposited thereonto, said distributor having an inlet and defining a flow path by which said two-phase mixture is dispersed across generally the entire length and width of said tube bundle prior to exiting said distributor, said distributor defining a distribution volume downstream of said flow path in flow communication therewith, the pressure in said distribution volume being lower than the pressure in said flow path, refrigerant flowing out of said flow path, into said distribution volume and impinging on a surface by which said distribution volume is defined so as to reduce the kinetic energy of said refrigerant prior to the delivery of the liquid portion thereof out of said distributor and into contact with said tube bundle.

A method of distributing two-phase refrigerant within the falling film evaporator of a refrigeration chiller comprising the steps of:

• disposing a tube bundle under a distributor within said evaporator;
• delivering two-phase refrigerant from an expansion device in said chiller into said distributor;
• flowing said two-phase refrigerant mixture within said distributor so as to position said mixture across the large majority of the length and width of said tube bundle internally of said distributor;
• reducing the kinetic energy of the two-phase refrigerant mixture internal of said distributor;
• and
• depositing liquid refrigerant in relatively low-velocity droplet form onto said tube bundle.

A method of distributing two-phase refrigerant, within a falling film evaporator in a refrigeration system, by use of a refrigerant distributor disposed internal of the evaporator shell and into which the two-phase mixture is received from an expansion device, comprising the steps of:

• positioning a tube bundle in said evaporator;
• positioning said distributor above said tube bundle so that said distributor generally overlies the top portion thereof;
• delivering two-phase refrigerant from said expansion device into said distributor;
• flowing, in a first flowing step, said two-phase refrigerant in a first direction and at an essentially constant speed through a first passage within said distributor;
• passing, in a first passing step, said two-phase mixture out of said first flow passage;
• flowing, in a second flowing step, said two-phase refrigerant in a second direction and at an essentially constant speed in a second flow passage within said distributor;
• passing, in a second passing step, said two-phase refrigerant mixture out of said second flow passage;
• reducing the pressure of the refrigerant delivered out of said second flow passage internal of said distributor to a pressure that is generally the same as the pressure exterior of the distributor within the evaporator shell;
• and
• depositing liquid refrigerant onto the upper portion of said tube bundle.