EP-4741741-A1 - CASCADE HEATING/COOLING SYSTEM WITH INTERMEDIATE LOOP HEAT EXCHANGE

Abstract

A heating, ventilation, air conditioning, and refrigeration (HVACR) system includes a first heat transfer circuit; a second heat transfer circuit; a fluid loop between the first heat transfer circuit and the second heat transfer circuit; a heat exchanger connecting to the fluid loop; and a controller. The controller is configured to determine an operation parameter of the system; and control the heat exchanger to remove heat from the fluid loop when the operation parameter is above a first threshold.

Inventors

• CLINE, Lee R
• KEYS, Daryl

Assignees

• Trane International Inc.

Dates

Publication Date

20260513

Application Date

20251111

Claims (15)

1. A heating, ventilation, air conditioning, and refrigeration (HVACR) system, the system comprising: a first heat transfer circuit; a second heat transfer circuit; a fluid loop between the first heat transfer circuit and the second heat transfer circuit; a heat exchanger connecting to the fluid loop; and a controller configured to: determine an operation parameter of the system; and control the heat exchanger to remove heat from the fluid loop when the operation parameter is above a first threshold.
2. The HVACR system of claim 1, wherein the controller is further configured to control the heat exchanger to add heat to the fluid loop when the operation parameter is below a second threshold.
3. The HVACR system of claim 1 or 2, wherein the first heat transfer circuit includes a fluid inlet configured to receive fluid from the fluid loop and a fluid outlet for fluid flowing out to the fluid loop, the first heat transfer circuit is configured to add heat to the fluid loop.
4. The HVACR system of claim 3, further comprising: a cooled loop configured to add heat to the fluid loop via the first heat transfer circuit, the cooled loop being a source of heat of the system.
5. The HVACR system of any one of claims 1 to 4, wherein the second heat transfer circuit includes a fluid inlet configured to receive fluid from the fluid loop and a fluid outlet for fluid flowing out to the fluid loop, the second heat transfer circuit is configured to remove heat from the fluid loop.
6. The HVACR system of claim 5, further comprising: a heated loop configured to remove heat from the fluid loop via the second heat transfer circuit, the heated loop being a sink of heat of the system.
7. The HVACR system of any one of claims 1 to 6, further comprising: a flow control device, the controller is further configured to control the flow control device to direct a fluid flow from the fluid loop to the heat exchanger when the operation parameter is above the first threshold.
8. The HVACR system of claim 7, wherein the controller is further configured to control the flow control device to direct the fluid flow from the fluid loop to the heat exchanger when the operation parameter is below a second threshold.
9. The HVACR system of claim 8, wherein the controller is further configured to control the flow control device to block the fluid flow from the fluid loop to the heat exchanger when the operation parameter is at or below the first threshold and is at or above the second threshold.
10. The HVACR system of any one of claims 1 to 9, wherein the operation parameter is a temperature of a fluid flow downstream of the first heat transfer circuit and upstream of the second heat transfer circuit.
11. A method of operating a heating, ventilation, air conditioning, and refrigeration (HVACR) system, the system including a first heat transfer circuit; a second heat transfer circuit; a fluid loop between the first heat transfer circuit and the second heat transfer circuit; a heat exchanger connecting to the fluid loop; and a controller, the method comprising: determining an operation parameter of the system; and controlling the heat exchanger to remove heat from the fluid loop when the operation parameter is above a first threshold.
12. The method of claim 11, further comprising: (i) controlling the heat exchanger to add heat to the fluid loop when the operation parameter is below a second threshold, or (ii) controlling a flow control device to direct a fluid flow from the fluid loop to the heat exchanger when the operation parameter is above the first threshold, or (iii) controlling a flow control device to direct a fluid flow from the fluid loop to the heat exchanger when the operation parameter is above the first threshold, and controlling the flow control device to direct the fluid flow from the fluid loop to the heat exchanger when the operation parameter is below a second threshold, or (iv) controlling a flow control device to direct a fluid flow from the fluid loop to the heat exchanger when the operation parameter is above the first threshold, controlling the flow control device to direct the fluid flow from the fluid loop to the heat exchanger when the operation parameter is below a second threshold, and controlling the flow control device to block the fluid flow from the fluid loop to the heat exchanger when the operation parameter is at or below the first threshold and is at or above the second threshold.
13. The method of claim 11 or 12, wherein (a) the first heat transfer circuit includes a fluid inlet configured to receive fluid from the fluid loop and a fluid outlet for fluid flowing out to the fluid loop, and the first heat transfer circuit is configured to add heat to the fluid loop, or wherein (b) the second heat transfer circuit includes a fluid inlet configured to receive fluid from the fluid loop and a fluid outlet for fluid flowing out to the fluid loop, the second heat transfer circuit is configured to remove heat from the fluid loop, or wherein (c) the operation parameter is a temperature of a fluid flow downstream of the first heat transfer circuit and upstream of the second heat transfer circuit.
14. The method of claim 13, wherein under (a), the system further comprises a cooled loop configured to add heat to the fluid loop via the first heat transfer circuit, the cooled loop being a source of heat of the system.
15. The method of claim 13 or 14, wherein under (b), the system further comprises a heated loop configured to remove heat from the fluid loop via the second heat transfer circuit, the heated loop being a sink of heat of the system.

Description

FIELD The embodiments described herein pertain generally to systems and methods for heat energy control of a heating, ventilation, air conditioning, and refrigeration (HVACR) system. More specifically, the embodiments described herein pertain to maintaining desired temperature in the intermediate loop of a cascade heating and/or cooling HVACR system in different modes of system operation. BACKGROUND A heating, ventilation, air conditioning, and refrigeration (HVACR) system may include one or more heat transfer circuits. A heat transfer circuit may include one or more compressors, a condenser, an evaporator, fans, filters, dampers, and various other equipment. The one or more compressors, the condenser, the expansion device, and the evaporator are fluidly connected. The heat transfer circuit can be a heat pump, a chiller, or the like. SUMMARY Features in the embodiments disclosed herein may enable and/or expand the application of an HVACR system including cascade heat transfer circuits such as vapor-compression chiller units and/or heat pump units. Features in the embodiments disclosed herein may also allow for reliable and/or long-term system operation when the operating capacities of the primary unit and the secondary unit of the cascade system are not synchronized. Features in the embodiments disclosed herein may aid in different system operation modes such as system start-up, stable operation, and intentional capacity mismatch (e.g., cooling-dominant system operation). Features in the embodiments disclosed herein may maintain a desired temperature in the intermediate loop of a cascade heating and/or cooling system in different modes of system operation. The modes include, but not limited to, system startup, unit(s) startup, individual unit capacity changes (e.g., loading, unloading, or the like), intentional cooling dominant operation, intentional heating dominant operation, unit(s) shutdown, and/or system shutdown. Features in the embodiments disclosed herein may prevent unacceptable temperature transients from occurring (during one or more of the operation modes) which may negatively impact system operation (e.g., supply of heating or cooling), causing unstable system and/unit(s) operation and impact unit(s) reliability, short or long term. In an example embodiment, a heating, ventilation, air conditioning, and refrigeration (HVACR) system is provided. The system includes a first heat transfer circuit; a second heat transfer circuit; a fluid loop between the first heat transfer circuit and the second heat transfer circuit; a heat exchanger connecting to the fluid loop; and a controller. The controller is configured to determine an operation parameter of the system; and control the heat exchanger to remove heat from the fluid loop when the operation parameter is above a first threshold. In an example embodiment, a method of operating a heating, ventilation, air conditioning, and refrigeration (HVACR) system is provided. The system includes a first heat transfer circuit; a second heat transfer circuit; a fluid loop between the first heat transfer circuit and the second heat transfer circuit; a heat exchanger connecting to the fluid loop; and a controller. The method includes determining an operation parameter of the system; and controlling the heat exchanger to remove heat from the fluid loop when the operation parameter is above a first threshold. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings illustrate various embodiments of systems, methods, and embodiments of various other aspects of the disclosure. Any person with ordinary skills in the art will appreciate that the illustrated element boundaries (e.g. boxes, groups of boxes, or other shapes) in the figures represent one example of the boundaries. It may be that in some examples one element may be designed as multiple elements or that multiple elements may be designed as one element. In some examples, an element shown as an internal component of one element may be implemented as an external component in another, and vice versa. Non-limiting and non-exhaustive descriptions are described with reference to the following drawings. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating principles. In the detailed description that follows, embodiments are described as illustrations only since various changes and modifications may become apparent to those skilled in the art from the following detailed description. FIG. 1 illustrates a schematic diagram of a controller subsystem, arranged in accordance with at least some embodiments described herein.FIG. 2A illustrates a schematic diagram of a cascade HVACR system, arranged in accordance with at least some embodiments described herein.FIG. 2B illustrates a schematic diagram of a cascade HVACR system, arranged in accordance with at least some embodiments described herein.FIG. 2C illustrates a schematic diagram of a cascade HVACR system, arrang