Some example embodiments relate to the field of circulating devices such as pumps, boosters and fans, and related systems.
In some conventional systems, manufacturer specifications for equipment are published with maximum load ratings. As an example, for fixed speed HVAC (heating, ventilation, and air conditioning) pump systems, performance criteria may be based on a narrow band of conditions, optimizing for occupant use during maximum load, which often meant sacrificing operating efficiency during part-load conditions.
Prior to variable speed drives, some conventional industry practices meant designing heating, cooling and plumbing system performance around a single point that represented the most extreme conditions or loads that a building might experience during its operating lifecycle.
A difficulty with some existing systems is that, at part-load, the pumping system may be susceptible to instability, poor occupant comfort and energy and economic wastage.
The traditional selection of a pump or pumps may result in wastage of resources and inefficient operation. Load limits for a building may vary so that the variable speed equipment, (e.g. pump, boiler plant, booster or other) may not be required to operate at full capacity to service the system requirements. Further, improper equipment selection may require a repair or total replacement of the equipment to a more suitable size of equipment (e.g. pump, boiler plant, booster, or other).
Additional difficulties with existing systems may be appreciated in view of the detailed description below.
In accordance with an example embodiment, there is provided a method for defining boundaries of a selection range for a variable speed device, the variable speed device being dependent on at least a first parameter and a second parameter, the first parameter and the second parameter being correlated. The method includes: determining a first boundary of the selection range defined by a reference to an efficiency curve of the variable speed device, determining a second boundary of the selection range based on a percentage of the efficiency curve, adjusting the first boundary or the second boundary based on a cost dependent on at least an operating cost of the variable speed device operating at part loads for a specified period of time, and displaying on a graphical interface screen a graph of the first parameter versus the second parameter, the graph having displayed thereon a region representing the selection range.
In accordance with another example embodiment, there is provided a computer system, including a controller and memory for storing information of a variable speed device, the variable speed device being dependent on at least a first parameter and a second parameter, the first parameter and the second parameter being correlated. The controller is configured to: determine a first boundary of the selection range defined by a reference to an efficiency curve of the variable speed device, determine a second boundary of the selection range based on a percentage of the efficiency curve, adjust the first boundary or the second boundary based on a cost dependent on at least an operating cost of the device operating at part loads for a specified period of time, and generate for display on a graphical interface screen a graph of the first parameter versus the second parameter, the graph having displayed thereon a region representing the selection range.
In accordance with yet another example embodiment, there is provided a non-transitory computer readable medium having instructions stored thereon executable by a processor for defining boundaries of a selection range for a variable speed device, the variable speed device being dependent on at least a first parameter and a second parameter, the first parameter and the second parameter being correlated, the instructions comprising: instructions for determining a first boundary of the selection range defined by a reference to an efficiency curve of the variable speed device; instructions for determining a second boundary of the selection range based on a percentage of the efficiency curve; instructions for adjusting the first boundary or the second boundary based on a cost dependent on at least an operating cost of the variable speed device operating at part loads for a specified period of time; and instructions for generating for display on a graphical interface screen a graph of the first parameter versus the second parameter, the graph having displayed thereon a region representing the selection range.
Embodiments will now be described, by way of example only, with reference to the attached Figures, wherein:
Like reference numerals may be used throughout the Figures to denote similar elements and features.
Example embodiments generally relate to circulating devices such as pumps, boosters and fans, and related systems.
In accordance with an example embodiment, there is provided a method for defining boundaries of a selection range for a variable speed device, the variable speed device being dependent on at least a first parameter and a second parameter, the first parameter and the second parameter being correlated. The method includes: determining a first boundary of the selection range defined by a reference to an efficiency curve of the variable speed device, determining a second boundary of the selection range based on a percentage of the efficiency curve, adjusting the first boundary or the second boundary based on a cost dependent on at least an operating cost of the variable speed device operating at part loads for a specified period of time, and displaying on a graphical interface screen a graph of the first parameter versus the second parameter, the graph having displayed thereon a region representing the selection range.
In accordance with another example embodiment, there is provided a computer system, including a controller and memory for storing information of a variable speed device, the variable speed device being dependent on at least a first parameter and a second parameter, the first parameter and the second parameter being correlated. The controller is configured to: determine a first boundary of the selection range defined by a reference to an efficiency curve of the variable speed device, determine a second boundary of the selection range based on a percentage of the efficiency curve, adjust the first boundary or the second boundary based on a cost dependent on at least an operating cost of the device operating at part loads for a specified period of time, and generate for display on a graphical interface screen a graph of the first parameter versus the second parameter, the graph having displayed thereon a region representing the selection range.
In accordance with yet another example embodiment, there is provided a non-transitory computer readable medium having instructions stored thereon executable by a processor for defining boundaries of a selection range for a variable speed device, the variable speed device being dependent on at least a first parameter and a second parameter, the first parameter and the second parameter being correlated, the instructions comprising: instructions for determining a first boundary of the selection range defined by a reference to an efficiency curve of the variable speed device; instructions for determining a second boundary of the selection range based on a percentage of the efficiency curve; instructions for adjusting the first boundary or the second boundary based on a cost dependent on at least an operating cost of the variable speed device operating at part loads for a specified period of time; and instructions for generating for display on a graphical interface screen a graph of the first parameter versus the second parameter, the graph having displayed thereon a region representing the selection range.
In accordance with an example embodiment, there is provided a method to define a selection range of an intelligent variable speed device or system, with an envelope border line, for a variety of design day conditions, that is defined to comply with industry standards and codes for part load performance (such as ASHRAE 90.1 standard for energy savings of 70% at 50% design day flow, 20:1 turn down capacity for a chiller plant).
Reference is first made to
As illustrated in
The control device 108 may include an internal sensor, sometimes referred to as a “sensorless” pump because an external sensor is not required. The internal sensor may detect, for example, the power and speed of the pump device 106. The pump speed of the pump device 106 may be varied to maintain the pressure setpoint in dependence of the internal sensor. A program map may be used by the control device 108 to map a detected power and speed to a resultant head and flow.
Referring still to
In some examples, the circulating system 100 may be a chilled circulating system (“chiller plant”). The chiller plant may include an interface 118 in thermal communication with a secondary circulating system for the building 104. The control valves 112a, 112b, 112c, 112d manage the flow rate to the cooling coils (e.g., load 110a, 110b, 110c, 110d). Each 2-way valve 112a, 112b, 112c, 112d may be used to manage the flow rate to each respective load 110a, 110b, 110c, 110d. As a valve 112a, 112b, 112c, 112d opens, the differential pressure across the valve decreases. The control device 108 responds to this change by increasing the pump speed of the pump device 106 to maintain the pressure setpoint. If a control valve 112a, 112b, 112c, 112d closes, the differential pressure across the valve increases, and the control device 108 responds to this change by decreasing the pump speed of the pump device 106 to maintain the pressure setpoint.
In some other examples, the circulating system 100 may be a heating circulating system (“heating plant”). The heater plant may include an interface 118 in thermal communication with a secondary circulating system for the building 104. In such examples, the control valves 112a, 112b, 112c, 112d manage the flow rate to heating elements (e.g., load 110a, 110b, 110c, 110d).
Referring still to
Reference is now made to
The design point can be estimated by the system designer based on the flow that will be required by a system for effective operation and the head/pressure loss required to pump the design flow through the system piping and fittings. Note that, as pump head estimates may be over-estimated, most systems will never reach the design pressure and will exceed the design flow and power. Other systems, where designers have under-estimated the required head, will operate at a higher pressure than the design point. For such a circumstance, one feature of properly selecting an intelligent variable speed pump is that it can be properly adjusted to delivery more flow and head in the system than the designer specified.
The graph 200 includes axes which include parameters which are correlated. For example, head squared is proportional to flow, and flow is proportional to speed. In the example shown, the abscissa or x-axis 204 illustrates flow in U.S. gallons per minute (GPM) and the ordinate or y-axis 206 illustrates head (H) in pounds per square inch (psi) (alternatively in feet). The range of operation 202 is a superimposed representation of the control pump 102 with respect to those parameters, onto the graph 200.
The relationship between parameters may be defined by particular affinity laws, which may be affected by volume, pressure, and Brake Horsepower (BHP). For example, for variations in impeller diameter, at constant speed:
D1/D2=Q1/Q2;H1/H2=D12/D22;BHP1/BHP2=D13/D23.
For example, for variations in speed, with constant impeller diameter:
S1/S2=Q1/Q2;H1/H2=S12/S22;BHP1/BHP2=S13/S23.
Wherein: D=Impeller Diameter (Ins/mm); H=Pump Head (Ft/m); Q=Pump Capacity (gpm/lps); S=Speed (rpm/rps); BHP=Brake Horsepower (Shaft Power−hp/kW).
As shown in
Other example control curves other than quadratic curves include constant pressure control and proportional pressure control. Selection may also be made to another control curve (not shown), depending on the particular application.
Reference is now made to
As an initial matter, reference is made to
Referring again to
For the control curve 208, with reference again to
The server system 530 may be configured as a web server which generates graphical user interface (GUI) screens for display on the client device 502. As shown in
The memory 522 of the server system 530 may include user information, which can include user information along with associated access rights. For example, a contractor/installer or sales representative may have read-only rights and some restricted access, while employees may have editing rights and/or further access rights. The memory 522 may also include a database of a plurality of devices such as control pumps 102, along with respective model numbers and ranges of operation 202, and design point regions 240 (see
The client device 502 may include one or more client applications 510. In some example embodiments, the client device 502 may include a controller 506 such as a microprocessor, which controls the overall operation of the client device 502. The controller 506 interacts with other device components such as memory 508, and system software 512 stored in the memory 508 for executing the applications 510, input/output subsystems 514 (e.g. a keyboard, mouse, touchpad, scrollwheel, and/or a display) and a communications subsystem 516. A power source 518 powers the client device 502.
Referring still to
In some conventional websites where a user wishes to find a suitable search results for narrowing selection of devices, typically a user is required to manually populate a number of input fields to input desired search parameters, in order to retrieve results of which devices may be appropriate. This may result in unnecessary keystrokes and inputs to the website. In some other conventional websites, devices may already be categorized into predetermined or hard-coded groups, so that all of the devices in a group are retrieved depending on the desired search parameters (e.g. all devices from a particular family or group of models). The predetermined groups may not provide suitable results to the user, as too many results may be displayed. This can provide excessive results and limits flexibility of displaying results for subsequent selection by a user. Also, the user may not be aware of which devices would be most appropriate, which may result in less than optimal selection of an inappropriate or inefficient device for the desired end use or design point.
Reference is now made to
As shown in
Various regions of the interface screen 600 may be navigated using an indicator 610, shown as a pointer arrow icon 640, which is overlaid onto the interface screen 600. The pointer arrow icon 640 may be controlled from an input device such as a mouse, touchpad, scrollball or touchscreen. The pointer arrow icon 640 may be used to select a point or region on the screen 600, which may be performed by selecting, e.g. clicking, from the input device. Further selection may also be performed, for example by “double clicking” using the input device, or other suitable user operations as appropriate such as “right clicking”, “middle clicking”, “thumb clicking”, etc., as would be understood in the art.
In the example embodiment shown, the graph 602 represents Head versus Flow. Each control pump 102 is represented on the graph 602 as a region, “design envelope”, or selection range within a composite of a group of design envelopes 612. Each design envelope 612 is based on the design point region 240 for each particular control pump 102.
As shown in
Reference is now made to
As shown in
In some example embodiments, still referring to
In some example embodiments, the selection of the particular point 628 or region 646 results in only the relevant design envelopes 612 being displayed (relevance described in detail herein below, which includes devices which are compliant with the selected point 628). In other words, the graph 602 is dynamically updated to remove the non-relevant design envelopes. In some example embodiments, the relevant design envelopes 612a are at least those having a design point region 240 (
Referring still to
As shown in
Referring still to
Reference is now made to
Referring still to
Referring still to
The stored inventory of pumps may be stored in memory 522 (
Example embodiments may have the priority of listing be at least based on part load operation of each device for a specified period of time. In some example embodiments, the initial selection of the highest priority order device may require that the lowest part load operating cost selection also be the lowest list price selection. If this is not the case, it is determined that the lowest operating cost difference requires a “payback” of the difference between the pricing of the higher list price and lower list price of the model with the higher operating cost. For example, this may be based on 3 years operation at $0.10/kWh (to assist in normalization, USD markets may calculate payback at a 0.50 discount level due to discounted pricing used in that market). If the payback were greater than 3 years the lower cost unit with the higher operating cost replaces the lowest operational cost unit as a higher-ranked selected unit.
Accordingly, a Calculate Cost Saving Index may be calculated for each item (e.g. control pump) using the following formula:
CSi=LPi+r*OCi;
wherein i is the current item, having a range of 1 . . . n (number of items in selection); LP is the item List Price (in dollars); OC is the item operating cost (e.g. cost per year operating at part loads according to the load profile); and r is the market index (in years, e.g. equals 6 for U.S. dollar market or 3 for other markets). The result of this stage is an array of indexes CS[n], wherein n is the total number of items in selection. The Cost Saving Index can represent a tradeoff of fixed cost for operating cost at various part loads over a specified time period, as determined by the load profile. The specified time period is typically greater than one year, and can be 3 years in some example embodiments. For example, 3 years is one regularly used industry acceptable payback period on the capital expenditure for items such as HVAC equipment.
The operating cost (OC) can be calculated based from the load profile, as shown in
Note that, 3 years is a conservative estimate of the market expectation of simple payback of value-added costs. In other example embodiments, the specified time period may be a typical expected lifetime of the item, for example on or about 20 years, or more in some examples. In reality, some devices can last much longer, to at least 35-40 years. In other example embodiments, a warranty period can be used as the specified time period.
As shown in
Referring again to event 1006, if the OC of a pump (i−1) is greater than an OC of the next highest pump (i) (if “no”), the method 1000 proceeds to event 1010 which calculates the Cost Savings Index (CS). At event 1012, it is determined whether the CS(i) is greater than the CS(i−1), and if not (if “no”), the higher listing priced item (i) is considered to have a higher priority ranking than the other item (i−1) and the rankings are switched. If so (if “yes”), this priority order stays the same and the method 1000 proceeds to event 1008 and the next item is considered (i=i+1). At event 1016, the final priority order ranking is completed for all items. The final priority order ranking may then be displayed, for example within the listing 902 (
In some example embodiments, the Cost Savings Index can be thought of as first calculating a Payback (PB)=LP(i−1)−LP(i). It can then be determined whether the PB is greater than the operating cost (OC) savings over the payback period of e.g. 3 years, wherein the OC savings are, e.g. OC(i)*r−OC(i−1)*r.
In some example embodiments, the cost savings index may be one factor used in combination or weighted with other factors in order to determine the priority order. Other example factors include but are not limited to: best value, best speed, lowest price, highest efficiency, closest to target growth capacity, closest to best efficiency point (BEP) flow (on average load flow), highest average load efficiency, lowest delta load efficiency, and lowest operating cost.
Thus, reference is now made to
For example, a difficulty with some existing conventional systems is that items may be listed in a predetermined order of model number or list price. This may not provide the user with the most relevant item from a cost perspective. Accordingly, an improper or sub-optimal item may be selected in such conventional systems.
Referring again to
The boundaries may be based on at least an efficiency curve of a device, such as a best efficiency point (BEP) curve 220 of a control pump 102, as would be understood in the art. The right-hand (RH) edge 224 of the design envelope may be based on, e.g. on or about 135% of the BEP curve 220. Note that the design point, point A (210), remains to the right of the BEP curve 220. Accordingly, the resultant range of operation 202 of the selected device may be optimized for partial load operation.
In other examples the design envelope may extend to on or about 10% to the left of BEP curve 220 and point A (210) may be selected in that region; however the energy savings may not be as significant as selecting to the right of the BEP curve 220.
For example, a difficulty with some traditional constant speed systems is that a design point (Point A) is selected to the left of the BEP curve, resulting in optimization only for full load operation. Some traditional constant speed pumps were sized slightly to the left of BEP curve so that if oversized, the duty would drift to the right and thus operate at BEP curve.
A low flow and head point 222 on the design envelope 240 may be defined by, e.g., on or about 63% of the flow value and on or about 40% of the maximum head value of the right-hand (RH) edge 224 of the design envelope 240. A low flow and head point 226 on the design envelope 240 may be defined by, e.g., on or about 63% of the flow value and on or about 40% of the maximum head value of the left-hand edge 230. In some example embodiments, a lower boundary 228 is defined by a pump speed curve (shown in Hertz; alternatively in rpm) between the low head point 222 and the low flow point 226. In other example embodiments, the lower boundary 228 is defined by a straight line which connects the low flow and head point 22 with the other low flow and head point 226.
The left-hand edge 230 of the design envelope 240 may be defined by the BEP curve 220. In some examples (not shown), the left-hand edge 230 of the design envelope 240 extends to the left of the BEP curve 220 up to and including the left-hand edge of the range of operation 202. The left-hand edge 230 of the design envelope 240 may be defined by another efficiency curve, such as a partial efficiency curve, such as a 77% efficiency curve 238.
In some example embodiments, the top edge 232 of the design envelope 240 may also be further defined by the motor power curve 236 (e.g. maximum horsepower) between the intersection of the left-hand edge 230 of the design envelope 240 (e.g. the BEP curve 220 or the 77% efficiency curve 238) with the power curve 236 and the right-hand edge 224 of the design envelope 240 with the power curve 236. In some example embodiments where the left-hand edge 230 of the design envelope 240 is to the left of the BEP curve 220, the top edge 232 boundary may be the pump speed curve operating at an appropriate or suitable speed (shown in Hz, such as pump speed curve 234) rather than a strict maximum motor power curve 236.
In some example embodiments, the motor power curve 236 may truncate a top-right boundary in some example embodiments. Thus, the electrical load limits of the particular control pump 102 may also at least partially define the design envelope 240.
It would be appreciated that example embodiments of the design envelope 240 comply with industry standards and codes for part load performance, such as ASHRAE 90.1 standard for energy savings of 70% at 50% design day flow, or 20:1 turn down capacity for a chiller plant.
In some example embodiments, separate design envelopes may be separately defined for each motor size of a given pump size.
Referring again to
Variations may be made in example embodiments. Some example embodiments may be applied to any variable speed device, and not limited to variable speed control pumps. For example, some additional embodiments may use different parameters or variables, and may use more than two parameters (e.g. three parameters on a three dimensional graph). For example, the speed (rpm) is also illustrated on the described control curves. Further, temperature (Fahrenheit) versus temperature load (BTU/hr) may be parameters or variables which are considered for control curves, for example controlled by a variable speed circulating fan. Note that pressure is proportional to temperature. Some example embodiments may be applied to any variable speed devices which are dependent on two or more correlated parameters. Some example embodiments can include selection ranges dependent on parameters or variables such as liquid, temperature, viscosity, suction pressure, site elevation and number of pump operating.
While some of the present embodiments are described in terms of methods, a person of ordinary skill in the art will understand that present embodiments are also directed to various apparatus such as a server apparatus including components for performing at least some of the aspects and features of the described methods, be it by way of hardware components, software or any combination of the two, or in any other manner. Moreover, an article of manufacture for use with the apparatus, such as a pre-recorded storage device or other similar non-transitory computer readable medium including program instructions recorded thereon, or a computer data signal carrying computer readable program instructions may direct an apparatus to facilitate the practice of the described methods. It is understood that such apparatus, articles of manufacture, and computer data signals also come within the scope of the present example embodiments.
While some of the above examples have been described as occurring in a particular order, it will be appreciated to persons skilled in the art that some of the messages or steps or processes may be performed in a different order provided that the result of the changed order of any given step will not prevent or impair the occurrence of subsequent steps. Furthermore, some of the messages or steps described above may be removed or combined in other embodiments, and some of the messages or steps described above may be separated into a number of sub-messages or sub-steps in other embodiments. Even further, some or all of the steps of the conversations may be repeated, as necessary. Elements described as methods or steps similarly apply to systems or subcomponents, and vice-versa.
The term “computer readable medium” as used herein includes any medium which can store instructions, program steps, or the like, for use by or execution by a computer or other computing device including, but not limited to: magnetic media, such as a diskette, a disk drive, a magnetic drum, a magneto-optical disk, a magnetic tape, a magnetic core memory, or the like; electronic storage, such as a random access memory (RAM) of any type including static RAM, dynamic RAM, synchronous dynamic RAM (SDRAM), a read-only memory (ROM), a programmable-read-only memory of any type including PROM, EPROM, EEPROM, FLASH, EAROM, a so-called “solid state disk”, other electronic storage of any type including a charge-coupled device (CCD), or magnetic bubble memory, a portable electronic data-carrying card of any type including COMPACT FLASH, SECURE DIGITAL (SD-CARD), MEMORY STICK, and the like; and optical media such as a Compact Disc (CD), Digital Versatile Disc (DVD) or BLU-RAY Disc.
Variations may be made to some example embodiments, which may include combinations and sub-combinations of any of the above. The various embodiments presented above are merely examples and are in no way meant to limit the scope of this disclosure. Variations of the innovations described herein will be apparent to persons of ordinary skill in the art having the benefit of the present disclosure, such variations being within the intended scope of the present disclosure. In particular, features from one or more of the above-described embodiments may be selected to create alternative embodiments comprised of a sub-combination of features which may not be explicitly described above. In addition, features from one or more of the above-described embodiments may be selected and combined to create alternative embodiments comprised of a combination of features which may not be explicitly described above. Features suitable for such combinations and sub-combinations would be readily apparent to persons skilled in the art upon review of the present disclosure as a whole. The subject matter described herein intends to cover and embrace all suitable changes in technology.
This application claims the benefit of priority to U.S. Patent Application No. 61/591,234, filed Jan. 26, 2012, the contents of which are herein incorporated by reference.
Filing Document | Filing Date | Country | Kind |
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PCT/CA2012/050776 | 11/1/2012 | WO | 00 |
Number | Date | Country | |
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61591234 | Jan 2012 | US |