CGAM Partial Heat Recovery Details

Issue:

Details on the CGAM PHR option

Resolution:

Partial heat recovery utilizes a supplemental heat exchanger mounted in series with the air-cooled condenser. The total heat recovered is roughly 25% of the total cooling load and the option also provides fan control to maintain pressure and temperature when the chiller is running at part load. There is one PFHE per circuit. 

The CGAM heat recovery option is a 316 Stainless brazed plate heat exchanger with copper braze, which would be considered single wall construction.

Do not use in a potable water application.

Must be selected with lanced aluminum, complete coat or copper as fin material and WIDE ambient application, which adds the VFD on the fans for adequate condenser pressure control.

For more information, see CGAM Partial Heat Recovery EB (CG-PRB014-EN12112012). 

Partial heat recovery piping information can be found in the current CGAM IOM CG-SVX17*-EN in the Installation - Mechanical section.

The BPHE waterside working pressure is rated at 150 psi. 

Operating Map:

The heat exchanger cannot operate without a load on the chiller and the minimum entering water temperature is 95°F.

Entering Water Temperature Range 95 - 140°F

Leaving Water Temperature Range 113 - 158°F

Delta T must be 18 degrees or less

For more information on the water piping, see Where can I find the piping for the partial heat recovery?

Pictures:

130T with PHR

Partial heat recovery with low temp or ice-making options:

A fast-acting discharge refrigerant temperature sensor is added to the CGAM, when ordered with one of these options:

• ice making
• low-temperature process
• partial heat recovery (PHR) control

For comfort cooling applications, the discharge temperature sensor is not required. CGAM chillers built with this discharge temperature sensor will have an additional level of safety during operation (which is not required for comfort cooling). The chiller controller does an estimation of pressure ratio based on refrigerant temperature and will limit the unit during a high-pressure ratio scenario.

The CGAM partial heat recovery, low temp, and ice-making options are mutually exclusive in TOPSS and Job Center. The chiller's compressors cannot handle the higher pressure ratio required for low leaving water temperatures paired with high condenser temps. It may be possible the chiller would operate at some lower evap temps without significant problems, but we will need to evaluate and test this more thoroughly for operating map and control constraints when paired with the PHR option. 

The low temp and partial heat recovery or partial heat recovery with ice-making may be available viaPueblo Design Specials.xlsx. The request must be approved by Engineering. Submit a request with a copy of your selection summary, job name, quantity, size of the unit(s), order entry date, sales office, and job contacts to SalesSupportPueblo@trane.com.

Once approved, you will need to select either "ice-making w/interface" or "low temp evap" in TOPSS. You will be issued a DSPA# which will need to be submitted with the order to reflect this change on the order.

Partial heat recovery cannot be operational at the same time the chiller is in ice build mode.

Additional Details for PHR with Ice Making:

When the CGAM chiller is being selected for ice making, the evaporator application needs to be selected for "Ice-mkg (20-65F/-7 to 18C) w/hard interf". This ensures the chiller will also have the hardware interface needed for the chiller to go into ice-making mode. The option includes dual setpoints for ice-making capability. The unit is automatically restricted to full load operation during the ice build mode. Information on the control of ice-making can be found in the IOM, under Installation-Electrical. CGAM Installation, Operation, and Maintenance (CG-SVX17L-EN_03122020) 

If Ice-making is not an option in TOPSS, select the glycol in the system first. This should allow the evaporator application of ice-making, as glycol is required.

If the CGAM was not ordered for ice-making, but the customer would like to change to allow ice-making, contact Field Modifications. They can be reached at 608-787-2924 or email abumodif@TRANE.com.

Like the low temperature process chiller, it includes additional controls and safeties, including the extra discharge temperature sensor.

Disallow Rules:

1. The CGAM with PHR when selected with MCHX (Microchannel condenser) as the fin material and HIGH ambient application for the condenser.

2. Partial heat recovery with low temp or ice-making options (see details above)

Notes:

Changes:

Other Question/Problem/Cause Statements:

• Is heat recovery available with this chiller?
• What is partial heat recovery?
• Why can't I select partial heat recovery in TOPSS?
• I can't choose heat recovery...
• Why is heat recovery so limited?
• What are the limitations for heat recovery on CGAM?
• Can we PHR on this chiller?

• Can the CGAM PHR option be used for potable water applications?

• Is the CGAM heat recovery option single wall or double wall?

• Is the PHR heat exchanger 316 Stainless steel?

• What is the PHR heat exchanger made of?

• Can I do a low temp evap and partial heat recovery option?
• Can I order a low temp evaporator and PHR?
• Is partial heat recovery available with a low-temperature evaporator?
• Can I do ice-making and the partial heat recovery option?

Facts:

• Air-Cooled Chiller (Pueblo) (CGAM 20-130 Ton)