WO2018217172A1 - Method and system for managing cooling load - Google Patents

Method and system for managing cooling load Download PDF

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Publication number
WO2018217172A1
WO2018217172A1 PCT/SG2018/050257 SG2018050257W WO2018217172A1 WO 2018217172 A1 WO2018217172 A1 WO 2018217172A1 SG 2018050257 W SG2018050257 W SG 2018050257W WO 2018217172 A1 WO2018217172 A1 WO 2018217172A1
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WO
WIPO (PCT)
Prior art keywords
cooling
supply
water
temperature
load
Prior art date
Application number
PCT/SG2018/050257
Other languages
French (fr)
Inventor
Yang Kwang FOO
Lee Peng GOH
Original Assignee
Singapore Power Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to SG10201704252P priority Critical
Priority to SG10201704252P priority
Application filed by Singapore Power Limited filed Critical Singapore Power Limited
Publication of WO2018217172A1 publication Critical patent/WO2018217172A1/en

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24FAIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F3/00Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems
    • F24F3/06Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the arrangements for the supply of heat-exchange fluid for the subsequent treatment of primary air in the room units
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24FAIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F3/00Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems
    • F24F3/12Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the treatment of the air otherwise than by heating and cooling
    • F24F3/14Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems characterised by the treatment of the air otherwise than by heating and cooling by humidification; by dehumidification
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24FAIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F13/00Details common to, or for air-conditioning, air-humidification, ventilation or use of air currents for screening
    • F24F13/20Casings or covers

Abstract

A district cooling system for servicing a plurality of nodes, said district cooling system comprising; at least one return system and at least one sensible cooling supply system, said sensible cooling supply system including a sensible cooling water supply and a supply pipe; wherein said sensible cooling water supply arranged to supply fluid at a temperature above a dehumidifying temperature, with said return system arranged to receive the returned water of said at least one supply system.

Description

METHOD AND SYSTEM FOR MANAGING COOLING LOAD
Field of the Invention
The invention relates to air-conditioning systems for cooling commercial and residential premises. In particular, the invention is directed to the management of the sensible and latent cooling load of said premises. Background
The capacity of air-conditioning systems is designed so as to manage the sensible and latent cooling load. The sensible cooling load of a building relates to the dry bulb temperature and is directed to an occupant's comfort related to temperature. The latent cooling load is directed to the wet bulb temperature and is directed to an occupant's comfort with respect to humidity.
Typically, the cooling load in a commercial building comprises 80-85% of the sensible load and 15-20% of the latent load. An air-conditioning system therefore must accommodate both loads in order to provide the required comfort for an occupant.
Each of the PAU's, AHU's and FCU's require a supply of chilled water for the coils. To manage the latent cooling load in Singapore the supply water must be around 7°C in order to remove moisture from the air, and thus manage humidity. To remove the sensible load, the AHU/PAU can operate at a higher temperature and may, for instance, be supplied with chilled water at approximately 12°C. Whilst, in general, such an arrangement operates well and is widely used, the implementation of a district cooling system may provide opportunities not available to stand alone air-conditioning systems. Summary of Invention
In a first aspect, the invention provides a district cooling system for servicing a plurality of nodes, said district cooling system comprising; at least one return system and at least one sensible cooling supply system, said sensible cooling supply system including a sensible cooling water supply and a supply pipe; wherein said sensible cooling water supply arranged to supply fluid at a temperature above a dehumidifying temperature, with said return system arranged to receive the returned water of said at least one supply system. In a second aspect, the invention provides an air handling unit comprising; a housing; a fan within said housing, said fan arranged to direct air flow across a cooling coil; said cooling coil arranged to receive cooled water at a temperature above a dehumidifying temperature, a return duct arranged to direct returned air flow into the housing; wherein the returned duct includes a dehumidifying coil, said dehumidifying coil arranged to dehumidify the returned air flow; such that the dehumidifying coil arranged to receive chilled water at a dehumidifying temperature.
In a third aspect, the invention provides a district cooling system comprising, a lower temperature cooling system; and a higher temperature cooling system, wherein return chilled water of the lower temperature cooling system is reused as supply chilled water of the higher temperature cooling system.
In a fourth aspect, the invention provides a district cooling system comprising, a latent load cooling system, comprising supply chilled water and return chilled water for removing latent load; and a sensible load cooling system, comprising supply cooled water and return cooled water for removing sensible load, wherein the return chilled water of the latent load cooling system is reused as the supply cooled water of the sensible load cooling system.
In a fifth aspect, the invention provides a district cooling system comprising, a latent load cooling system, comprising supply chilled water and return chilled water for removing latent load; and a sensible load cooling system, comprising supply cooled water and return cooled water for removing sensible load, wherein temperature of the supply chiller water is set to be capable to remove latent load and temperature of the supply cooled water is higher than the temperature of the supply chiller water.
In general, the invention provides for a district cooling system having a plurality of nodes, said district cooling system having at least one return and two supply systems, said supply systems supplying fluid at differential temperatures to the nodes, with said return receiving the returned water corresponding to both supply systems.
The nodes in this case may be for residential, commercial or industrial use. For instance, the residential and commercial nodes may be hotels, office buildings, shopping malls etc. The residential nodes may be apartment buildings.
The at least two supply systems may be supplying fluid (such as water) at differential temperatures, for instance chilled water at 7°C and cooled water at 12°C. The supply systems may be localized, having localized cooling systems, or may be networked for the entire district cooling.
It will be appreciated that to reduce infrastructure the chilled water may be localized, whilst the cooled supply system may be a more broad implemented system. Such a system may be advantageous for implementation into existing infrastructure or commercial development (Brown Field). For a green field development, such as a new residential estate, the introduction of complete supply systems may be more
advantageous.
It will be further appreciated that, based on seasonal use, the same supply and/or return systems may be used for both heating and cooling. This may be subject to an intervening period during which the system is modified during off-season changes, for instance cooling to heating as the season changes from summer to winter.
The return system may be in fluid communication with said at least two supply systems, via cooling systems. To this end, the return system may return a portion of the total fluid to a chilled supply via a higher energy cooling system and return the remaining fluid to the other supply through a lower energy cooling system.
In the case of the return system having fluid at, say, 17°C, a smaller proportion of water may be supplied, via a chiller, to the chilled water supply and so require a temperature drop from 17°C to 7°C.
A higher proportion of water may be directed to the cooled water supply, via a cooler, to drop the temperature from 17°C to 12°C.
Thus, the district cooling system according to the present invention may have the advantage of directing only the minimum required volume of return water to the chiller rather than the entire volume. This may represent a considerable energy saving by cooling, rather than chilling, the greater proportion of supply water. Brief Description of Drawings
It will be convenient to further describe the present invention with respect to the accompanying drawings that illustrate possible arrangements of the invention. Other arrangements of the invention are possible and consequently, the particularity of the accompanying drawings is not to be understood as superseding the generality of the preceding description of the invention. Figures 1 is a schematic view of an AHU according to one embodiment of the present invention.
Figure 2 is a schematic view of a water chilling plant for a district cooling system according to a further embodiment of the present invention.
Figure 3 is a district cooling system according to a further embodiment of the present invention.
Figure 4 is a district cooling system according to a further embodiment of the present invention.
Detailed Description
In terms of the airside equipment, this typically comprises a building mounted primary air handling unit (PAU) drawing outside air into the unit, and moving the outside air via fans across cooling coils (or heating as required). Returned air exiting from PAU is then directed through air handling units (AHU) which are of a similar structure to the PAU but are generally regional (such as 1 AHU per floor) as compared to the PAU being building mounted.
The building may further include an array of fan coil units (FCU) which are a smaller and simpler version providing a fan to draw air across coils for servicing specific areas within the building. Figure 1 shows an air handling unit 5 according to one embodiment of the present invention. Consistent with a conventional AHU, it includes a housing 10 and a fan 20 for passing air through a cooling coil 15 and so supplying air 35 to the area in question. Outside air 45 is provided by a primary air handling unit (not shown) which delivers air 47 to the fan 20. Return air 40 is also directed 47 into the AHU.
Where the present embodiment differs from the conventional system is, first, with the cooling coil. Typically the cooling coil will receive chilled water at 7°C and return water at approximately 12°C. In the current case the cooling coil 15 is specifically directed to managing the sensible cooling load only and so has an input chilled water temperature of 12°C returning water 65 at 17°C. The AHU 5 according to the present embodiment further includes a dehumidifying coil 25 which receives chilled water at 7°C and therefore meeting the required temperature to draw moisture from the air. The returned chilled water 55 is then fed into the supply water 60 of the AHU 5 at 12°C.
Thus, the dehumidifying coil 25 manages the latent cooling load and together the AHU 5, which may be built into the infrastructure of the building behind a wall 30, is arranged to handle both the sensible and latent cooling load as required. As will be described below the AHU 5 according to this embodiment may also be in fluid communication with a district cooling system whereby chilled water at 12°C is provided as a supply to the cooling coil 15 and returned to the district cooling returned pipe at 17°C. The dehumidifying coil can therefore be supplied with the chilled water at 7°C by a resident chiller.
In a still further embodiment to be described below, a district cooling system according to one embodiment may have two parallel chilled water supply pipes with one chilled water supply pipe providing chilled water at 12°C and another at 7°C. It will be appreciated that in this further embodiment the supply to the dehumidification coil and supply to the cooling coil may both be provided by the supply pipes of a three pipe district cooling system. Figure 2 shows a schematic view of a chilling array 70 for a district cooling system according to one embodiment of the present invention. Here, large capacity chillers 75 are fed returned chilled water at 17°C through returned pipes 85. The large capacity chillers 75 supply chilled water at 12°C through chilled water supply pipes 90 for end users 105. In this embodiment, an array of small capacity chillers 80 also receiving returned chilled water at 17°C from the users 100 being serviced by the system. The small capacity chillers require high energy input but for lower volumes so as to provide chilled water at 7°C to a chilled water receiver 1 10 through supply pipes 95.
The larger capacity chillers 75 are intended to provide chilled water at 12°C for managing the sensible cooling load for users 105 and the smaller chillers 80 are intended to provide chilled water at 7°C and so manage the latent cooling load for users 1 10. Thus the chilling array 70 represents the supply for a three pipe cooling system according to one embodiment of the present invention. With the proportion of chilled water for sensible cooling loads being in the range 80-85% of a typical commercial building and the latent cooling load requiring lower temperature chilled water in the range 15-20%, the supply provided by the chiller array 70 is designed to provide sufficient chilled water at the specified differential temperatures. This compares to a conventional system which would need to provide chilled water at 7°C in a two pipe arrangement even though 80-85%) of the cooling load requires chilled water at the higher temperature. Only a small proportion, for instance 15-20%, needs to be at 7°C in order to dehumidify air within the respective buildings, which represents a significant energy saving. On the basis that the return temperature is 17°C the vast majority of the supply water need only be chilled to a fraction of the temperature done previously.
Figure 3 shows one example of a district cooling system 115 according to the present invention. Here, a supply pipe 120 providing chilled water at 12°C (or, at least, a temperature higher than a dehumidifying temperature (such as 7°C) variously supplies water 130 to nodes within the district. The nodes in this example are designated Building 1, 2 and 3. The nodes may also be clusters of residential properties or commercial properties (including hotels and resorts). In this example, the buildings return the water 135 to return pipes 125 typically at the higher temperature, for instance at 17°C. It will be appreciated that 12°C and 17°C are relative measures and both may be several degrees higher or lower depending upon circumstances.
Thus, the district cooling system 1 15 benefits from the energy saving of having a supply temperature higher than that required for the latent cooling load. In order for the buildings to receive chilled water to manage the latent cooling load, each may have a separate chiller providing water 140 which is subsequently delivered to the buildings 145. In the embodiment shown in Figure 3 the latent cooling load may be provided locally from a site specific chilled water source, the site specific chilled water source including a chiller having a capacity sufficient to provide chilled water at 7°C for that specific node. By having a district cooling system with a supply system directed to providing chilled water for the sensible cooling load, the temperature may be considerably higher than a conventional system, but sufficient to manage the design cooling load. In a still further embodiment, the return water 125 may still be of a sufficient temperature to be useful for outdoor cooling 150, 155 using various application.
Figure 4 shows the implementation of a district cooling system according to a still further embodiment of the present invention. A district cooling system 175 may receive supply 120 and return 125 chilled water with the supply water being at a temperature consistent with managing the sensible cooling load.
In this embodiment a second supply pipe 165 provides supply water at a dehumidifying temperature such as 7°C with the supply providing the lower temperatures supply water to specific locations 170. It will be appreciated therefore, under various embodiments of the present invention, that the district cooling system 160 shown in Figure 4 may provide a latent cooling load supply water to all of the users within the system or to selective users within the system. This may be by a subscription with specific users paying extra to receive the lower temperature supply water. Alternatively, the embodiment in Figure 4 may show an existing building 175 already having a single supply pipe 120 and providing the lower temperature chilled water through a locally sourced chiller (not shown). However, for a new development 180 the second pipe 165 may be installed for the new estate 180 as part of the installation of new infrastructure.
Thus, Figure 4 may be an example of a hybrid, for new development 180 with existing development 175 or demonstrate that the system 160 may provide chilled water for latent cooling load as a subscription arrangement. The logical progression of Figure 4 is a system whereby all the estates and all buildings serviced by the district cooling system 160 may be serviced by the three pipe system of two chilled water supply 120, 165 and a single returned pipe 125.

Claims

1. A district cooling system for servicing a plurality of nodes, said district cooling system comprising;
at least one return system and at least one sensible cooling supply system, said sensible cooling supply system including a sensible cooling water supply and a supply pipe;
wherein said sensible cooling water supply arranged to supply fluid at a temperature above a dehumidifying temperature, with said return system arranged to receive the returned water of said at least one supply system.
The district cooling system according to claim 1 , wherein at least a portion of said nodes are arranged to receive chilled water for managing a latent cooling load from a local site specific chilled water source.
The district cooling system according to claim 1 , further including at least one latent cooling supply system, said latent cooling supply system including a latent cooling water supply and a supply pipe;
wherein said latent cooling water supply arranged to supply fluid at a
dehumidifying temperature, with said return system arranged to receive the returned water of both supply systems.
4. The district cooling system according to claim 3, wherein the supply for the
latent cooling supply system is less than or equal to 20% of the combined supply.
5. The district cooling system according to any one of claims 1 to 4, wherein the dehumidifying temperature is 7°C.
6. An air handling unit comprising;
a housing; a fan within said housing, said fan arranged to direct air flow across a cooling coil;
said cooling coil arranged to receive cooled water at a temperature above a dehumidifying temperature.
a return duct arranged to direct returned air flow into the housing;
wherein the returned duct includes a dehumidifying coil, said dehumidifying coil arranged to dehumidify the returned air flow;
such that the dehumidifying coil arranged to receive chilled water at a dehumidifying temperature.
7. The air handling unit according to claim 6, wherein the cooled water for the cooling coil is received from a sensible cooling supply system of a district cooling system according to any one of claims 1 to 5.
The air handling unit according to claim 6 or 7, wherein the chilled water for the dehumidifying coil is received from a latent cooling supply system of a district cooling system according to any one of claims 3 to 5.
The air handling unit according to any one of claims 6 to 8, wherein the dehumidifying temperature is 7°C.
10. A district cooling system comprising,
a lower temperature cooling system; and
a higher temperature cooling system,
wherein return chilled water of the lower temperature cooling system is reused as supply chilled water of the higher temperature cooling system.
1 1. A district cooling system comprising, a latent load cooling system, comprising supply chilled water and return chilled water for removing latent load; and
a sensible load cooling system, comprising supply cooled water and return cooled water for removing sensible load,
wherein the return chilled water of the latent load cooling system is reused as the supply cooled water of the sensible load cooling system.
12. A district cooling system comprising,
a latent load cooling system, comprising supply chilled water and return chilled water for removing latent load; and
a sensible load cooling system, comprising supply cooled water and return cooled water for removing sensible load,
wherein temperature of the supply chiller water is set to be capable to remove latent load and temperature of the supply cooled water is higher than the temperature of the supply chiller water.
PCT/SG2018/050257 2017-05-24 2018-05-24 Method and system for managing cooling load WO2018217172A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
SG10201704252P 2017-05-24
SG10201704252P 2017-05-24

Publications (1)

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WO2018217172A1 true WO2018217172A1 (en) 2018-11-29

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PCT/SG2018/050257 WO2018217172A1 (en) 2017-05-24 2018-05-24 Method and system for managing cooling load

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3350892A (en) * 1966-04-04 1967-11-07 Midland Ross Corp Two-stage air conditioning system
US4164125A (en) * 1977-10-17 1979-08-14 Midland-Ross Corporation Solar energy assisted air-conditioning apparatus and method
JP2015059692A (en) * 2013-09-18 2015-03-30 新晃工業株式会社 Air conditioning system
WO2017173239A1 (en) * 2016-03-31 2017-10-05 Oceaneering International, Inc. Membrane microgravity air conditioner
WO2018070421A1 (en) * 2016-10-14 2018-04-19 荏原実業株式会社 Air conditioner

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3350892A (en) * 1966-04-04 1967-11-07 Midland Ross Corp Two-stage air conditioning system
US4164125A (en) * 1977-10-17 1979-08-14 Midland-Ross Corporation Solar energy assisted air-conditioning apparatus and method
JP2015059692A (en) * 2013-09-18 2015-03-30 新晃工業株式会社 Air conditioning system
WO2017173239A1 (en) * 2016-03-31 2017-10-05 Oceaneering International, Inc. Membrane microgravity air conditioner
WO2018070421A1 (en) * 2016-10-14 2018-04-19 荏原実業株式会社 Air conditioner

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