Patent Application
20200124311
The present disclosure relates generally to the field of heating, ventilation and air conditioning (HVAC) technology.
The following paragraphs are not an admission that anything discussed in them is prior art or part of the knowledge of persons skilled in the art.
U.S. Pat. No. 8,939,826 discloses an apparatus for heating, ventilation and/or air conditioning of an interior space, which includes a heat exchanger core and a heating/cooling device in fluid connection with the heat exchanger core. A recirculation port is arranged between a supply air chamber and an outside air chamber. A damper is adapted to move between a first position in which the damper blocks the recirculation port and a second position in which the recirculation port is unblocked. When the damper is in the second position, at least a portion of supply air is guided to flow from the supply air chamber through the outside air chamber to the heat exchanger core so as to defrost the heat exchanger core.
The following is intended to introduce the reader to the detailed description that follows and not to define or limit the claimed subject matter.
In an aspect of the present disclosure, an apparatus for heating, ventilation and/or air conditioning of an interior space of a structure can include: a housing including a recirculation air inlet, a recirculation air outlet, a fresh air inlet, and a fresh air outlet; a heat exchanger core arranged in the housing and including a first side and a second side segregated from the first side, the first side being in fluid connection with the recirculation air outlet, the second side being in fluid connection with the fresh air outlet; a recirculation air chamber arranged between the recirculation air inlet and the first side of the heat exchanger core, the recirculation air chamber including a recirculation air blower; a fresh air chamber arranged between the fresh air inlet and the second side of the heat exchanger core, the fresh air chamber including a fresh air blower; at least one sensor configured to collect pressure data related to at least one of the first and second sides of the heat exchanger core; and a control component configured to adjust operation of at least one of the recirculation air blower and the fresh air blower based on the pressure data.
In an aspect of the present disclosure, the control component is configured to adjust operation of at least one of the recirculation air blower and the fresh air blower step to reduce a difference in pressure between the first and second sides of the heat exchanger core.
In an aspect of the present disclosure, the at least one sensor includes a differential pressure sensor, and the control component is configured to receive the pressure data from the differential pressure sensor.
In an aspect of the present disclosure, the at least one sensor includes a first sensor for measuring a pressure in the first side of the heat exchanger core and a second sensor for measuring a pressure in the second side of the heat exchanger core, and the control component is configured to receive the pressure data from the first and second sensors.
In an aspect of the present disclosure, the control component includes a processor for comparing the pressures in the first and second sides of the heat exchanger core.
In an aspect of the present disclosure, when the pressure in the second side of the heat exchanger core is greater than the pressure in the first side of the heat exchanger core, the control component is configured to increase a duty cycle and/or speed of the recirculation air blower and/or decrease a duty cycle and/or speed of the fresh air blower.
In an aspect of the present disclosure, when the pressure in the first side of the heat exchanger core is greater than the pressure in the second side of the heat exchanger core, the control component is configured to increase a duty cycle and/or speed of the fresh air blower and/or decrease a duty cycle and/or speed of the recirculation air blower.
In an aspect of the present disclosure, the control component includes: a processor configured to receive the pressure data from the at least one sensor; a recirculation air fan motor controller operatively coupled to the recirculation air blower and the processor; and a fresh air fan motor controller operatively coupled to the fresh air blower and the processor.
In an aspect of the present disclosure, the apparatus includes a heating/cooling device.
In an aspect of the present disclosure, a method of heating, ventilation and/or air conditioning of an interior space of a structure involves: operating a recirculation air blower at a first initial speed to guide recirculation air from the interior space to flow to a first side of a heat exchanger core; guiding the recirculation air from the first side of the heat exchanger core to be expelled to outside of the interior space; operating a fresh air blower at a second initial speed to guide fresh air to flow to a second side of the heat exchanger core; guiding the fresh air from the second side of the heat exchanger core to be delivered to the interior space; collecting pressure data related to at least one of the first and second sides of the heat exchanger core; and based on the pressure data, adjusting at least one of the first initial speed and the second initial speed.
In an aspect of the present disclosure, the step of adjusting involves adjusting at least one of the first and second initial speeds to reduce a difference in pressure between the first and second sides of the heat exchanger core.
In an aspect of the present disclosure, the step of collecting involves measuring a differential pressure between the first and second sides of the heat exchanger core.
In an aspect of the present disclosure, the step of collecting involves measuring pressures in each of the first and second sides of the heat exchanger core.
In an aspect of the present disclosure, when the pressure in the second side is greater than the pressure in the first side, the step of adjusting involves at least one of increasing the first initial speed and decreasing the second initial speed.
In an aspect of the present disclosure, when the pressure in the first side is greater than the pressure in the second side, the step of adjusting involves at least one of increasing the second initial speed and decreasing the first initial speed.
In an aspect of the present disclosure, the method involves guiding the fresh air through a heating/cooling device prior to being delivered to the interior space.
Other aspects and features of the teachings disclosed herein will become apparent, to those ordinarily skilled in the art, upon review of the following description of the specific examples of the present disclosure.
The drawings included herewith are for illustrating various examples of apparatuses and methods of the present disclosure and are not intended to limit the scope of what is taught in any way. In the drawings:
Various apparatuses or methods will be described below to provide an example of an embodiment of each claimed invention. No embodiment described below limits any claimed invention and any claimed invention may cover apparatuses and methods that differ from those described below. The claimed inventions are not limited to apparatuses and methods having all of the features of any one apparatus or method described below, or to features common to multiple or all of the apparatuses or methods described below. It is possible that an apparatus or method described below is not an embodiment of any claimed invention. Any invention disclosed in an apparatus or method described below that is not claimed in this document may be the subject matter of another protective instrument, for example, a continuing patent application, and the applicant(s), inventor(s) and/or owner(s) do not intend to abandon, disclaim or dedicate to the public any such invention by its disclosure in this document.
An apparatus for heating, ventilation and/or air conditioning (HVAC) of an interior space of a structure can include a Heat Recovery Ventilator (HRV)/Energy Recovery Ventilator (ERV) unit, such as disclosed in U.S. Pat. No. 8,939,826 and issued Jan. 27, 2015, which is hereby incorporated by reference in its entirety.
Generally, the HRV/ERV unit uses recirculation air to precondition fresh air, to exchange heat or heat and moisture. But for the HRV/ERV unit, the recirculation air would be discharged outside of the interior space. Using the recirculation air is desirable as it provides a more efficient system, which in turn increases energy savings of heating, ventilation, and/or air conditioning the interior space.
The HRV/ERV unit can transfer heat and/or humidity levels from the recirculation air stream exiting the apparatus back to the fresh air stream entering the apparatus. A heat exchanger core in the using HRV/ERV unit can include a membrane system that allows for the transfer of this otherwise wasted energy from the discharge to the intake without actually mixing the stale air with the fresh new air.
Referring now to
The housing 120 is shown to include openings which define a recirculation air inlet 118, a fresh air inlet 116, a recirculation air outlet 138, and a fresh air outlet 136. Ductwork (not shown) can be connected to the apparatus 100 at the recirculation air inlet 118 to guide and deliver air from the interior space to the apparatus 100, at the fresh air inlet 116 to guide and deliver air from outside to the apparatus 100, at the recirculation air outlet 138 to guide air to be expelled or discharged outside of the interior space, and at the fresh air outlet 136 to deliver fresh air to the interior space. Normal variations in building construction can result in differences in the ductwork connected to the apparatus, and in particular, the air flow paths to the fresh air inlet 116 and the recirculation air inlet 118.
The apparatus 100 also includes a partition wall defining a recirculation air chamber 124 and a fresh air chamber 122, respectively, a recirculation air blower 128 is installed in the recirculation air chamber 124, and a fresh air blower 126 installed in the fresh air chamber 122.
Each of the blowers 126, 128 can consist of a centrifugal fan (e.g., high static with forward-curved blades) powered by an electric motor 132, 134, respectively, which can be a permanent-split capacitor (PSC) motor or an electronically commutated motor (ECM). Each of the blowers 126, 128 can be configured to have a single speed (for example, 75 cubic feet per minute (CFM)), two speeds (for example, 35-45 CFM and 75 CFM), or in some cases more than two speeds (for example, 4 speeds such as 25 CFM, 50 CFM, 75 CFM and 100 CFM). In other examples, the air flow can be higher than 100 CFM.
The heat exchanger core 130 has a first side and a second side that can be segregated from one another, so that there is generally no mixing of the streams of recirculation air and fresh air. However, heat (examples in which the heat exchanger core 130 is an HRV device) or heat and humidity (examples in which the heat exchanger core 130 is an ERV device) is exchanged between the recirculation air and the fresh air.
In operation, the recirculation air blower 128 draws in recirculation air or exhaust air (such as air from the interior space) from the recirculation air inlet 118, through the recirculation air chamber 124 to a first side of the heat exchanger core 130. Recirculation air can then travel through the first side of the heat exchanger core 130 between a first face 140a and a second face 140b opposite the first face 140a, generally along direction 142a. After travelling through the first side of the heat exchanger core 130, recirculation air is guided to the recirculation air outlet 138 to be expelled, or vented outside of the interior space.
Similarly, the fresh air blower 126 draws in fresh air, or outside air (such air from outside of the interior space) from the fresh air inlet 116, through the fresh air chamber 122 to a second side of the heat exchanger core 130. Fresh air can then travel through a second side of the heat exchanger core 130 between a third face 140c and a fourth face 140d opposite the third face 140c, generally along direction 142b. After travelling through the second side of the heat exchanger core 130, fresh air is guided to the fresh air outlet 136 to be delivered to the interior space.
The components of apparatus 100 are shown in
In some examples, the apparatus 100 includes a heating/cooling device, such as a VFC unit, and the fresh air can be guided to the heating/cooling device prior to being expelled in the interior space. That is, the fresh air from the second side of the heat exchanger core can be guided to flow through a heating/cooling device after the fresh air outlet 136.
Differences in air flow paths in the first side and the second side of the heat exchanger core 130 can result in unequal static pressures on the first and second sides of the heat exchanger core 130. In accordance with the teachings of the present disclosure, the apparatus 100 can be operated such that the heat exchanger core 130 has substantially equal static pressures on the first and second sides, and therefore can maintain a net zero pressure effect on the apparatus 100. If the static pressure on the first side and second side are different, the apparatus 100 can have an uncontrolled and potentially non-zero pressure effect on the interior space, pressurizing or depressurizing the interior space, both of which can be undesirable. Furthermore, due to the relation between motor pressure and motor speed, high static pressure can result in excessive stress on motors 132, 134, which reduces the lifetime of the motors 132, 134.
The control component 102 facilitates the operation of the apparatus 100. The control component 102 can include a processor 104 such as a programmable processing device, microprocessor, microcontroller, controllers, Central Processing Unit (CPU), and the like that can provide sufficient processing power depending on the configuration, purposes, and requirements of the apparatus 100, along with a suitable memory for storing control software. The control component 102 can control the electrical devices of the apparatus 100, such as motors 132, 134. The control component 102 can include fan motor controllers 106, 108 for controlling the motors 132, 134, respectively. The control component 102 can include a control board on which the fan motor controllers 106, 108 are located.
The control component 102 can be linked to an input device (for example, a touchscreen), and can be electronically connected to the various electronic devices of the apparatus 100, including the sensor 110, the motors 132, 134 of the blowers 128, 126, and electronic devices of the heating/cooling device. The processor 104 can communicate with the sensor 110 and the fan motor controllers 106, 108 over a wide geographic area via a network (not shown in
Although only one processor 104 and two fan motor controllers 106, 108 are shown in
The processor 104 can be configured to control the operation of the apparatus 100 according to the methods described herein. The processor 104 can include modules that initiate and manage the operations of the apparatus 100. The processor 104 can determine, based on received data, stored data and/or user preferences, how the apparatus 100 generally operates.
At least one sensor can collect data from the apparatus 100. In the example illustrated, the sensor 110 can be a pressure sensor to measure a pressure in the apparatus 100. In some examples, the sensor 110 can be a differential pressure sensor to measure a pressure difference between the first side and the second side of the heat exchanger core 130. For example, and not intended to be limiting, the sensor 110 can be a MEMS differential pressure sensor, such as a Siargo™ FSP1000 sensor. Although only the sensor 110 is shown in
In the example illustrated, the sensor 110 is coupled to or near the exhaust air ports of the heat exchanger core 130 via sample tubing 112, 114. The sample tubing 112, 114 can be formed of a flexible material, such as plastic or rubber, or other appropriate material. The sample tubing 112 can couple a first port of the sensor 110 to a component in fluid communication with the first side of the heat exchanger core 130, and the sample tubing 114 can couple a second port of the sensor 110 to a component in fluid communication with the second side of the heat exchanger core 130. As shown in
The sensor 110 can provide an analog voltage output and/or a digital bit stream indicative of a measured differential pressure level. In some examples, in which the sensor 110 generates analog voltage output, the analog voltage output can range from a minimum voltage value to a maximum voltage value.
For example, the range of the analog voltage output can be about 400 millivolts (mV) to about 2400 mV. Furthermore, the range of the analog voltage output can relate to a maximum negative pressure difference and a maximum positive pressure difference between the first side and the second side of the heat exchanger core 130. For example, the maximum negative pressure difference can be about −250 Pascals (Pa), or about −1 in WC, and the maximum positive pressure difference can be about +250 Pa, or about +1 in WC. For the analog voltage output range of 400 mV to 2400 mV, an analog voltage output of 1400 mV can indicate a net zero pressure difference, or about 0 Pa or about 0 in WC.
The maximum negative and positive pressure differences can be selected based on a maximum static pressure experienced by the apparatus 100. For example, the maximum positive and negative pressure differences can be about +1 in WC and −1 in WC, respectively when the maximum static pressure is about 0.8 WC.
The maximum static pressure can be predetermined based on laboratory testing and calculations of the resistance to air flow experienced by the apparatus 100 due to a given ducting arrangement, that is, the ductwork connected to the apparatus 100 for supplying fresh air and recirculation air. The laboratory testing can be performed using scaled models of the given ducting arrangement.
For example, the ducting arrangement can be the duct work for a typical interior space having an average layout of approximately 35 feet of 5″ round ducting and five elbows. Laboratory testing can determine that such a ducting arrangement can result in friction losses of approximately 0.318 in WC static pressure for each of the fresh air supply (SPFresh Air) and the recirculation air supply (SPRecirculation Air). In addition, some margin can be added to the static pressure to account for leakage in the ducting and/or variations in the layout. Any appropriate margins can be used. For example, an appropriate leakage margin can be about 5% and an appropriate safety margin can be about 20% for variations in the layout. Thus, based on Equation (1), the maximum static pressure (SPmax) can be about 0.8 in WC. Furthermore, the apparatus 100 can be designed with air blowers 126, 128 and motors 132, 134 to handle the maximum static pressure, such as 0.8 in WC.
The output of the sensor 110, that is, the pressure measurements can be transmitted to the processor 104. The processor 104 can receive the pressure measurements from the sensor 110 and control the operation of the apparatus 100 based on the received pressure measurements. For example, the processor 104 can control the fan motors 132, 134 based on the pressure data provided by the sensor 110. The processor 104 can control the fan motors 132, 134 via the fan motor controllers 106, 108, respectively. By controlling the fan motors 132, 134 based on the pressure measurements provided by the sensor 110, the apparatus 100 can make decisions on how best to compensate for differences, namely resistance differences, in air flow paths to the first side and the second side of the heat exchanger core 130 and downstream ducting variations.
The fan motor controllers 106, 108 can control the operation of the fan motors 132, 134 (for example, on or off) and the speed of the fan motors 132, 134. The speed of the fan motors 132, 134 can be represented in revolutions per minute (rpm). In some examples, the fan motors 132, 134 can operate at one of a plurality of speeds. The plurality of speeds can range from a low power speed or minimum speed to a high power speed or maximum speed.
Furthermore, for a given blower having a given fan and fan motor, the fan motor speeds (e.g., rpm) can be correlated to air flow rates (e.g., CFM) through the respective first or second side of the heat exchanger core 130. The air flow rates can be represented in cubic feet per minute (CFM) at inches of water column (in WC) static pressure. For example, the plurality of fan motor speeds can relate to air flow rates from about 25 (low speed), 50, 75, 100, and 125 (maximum speed) CFM at pressures from 0 static pressure to greater than 0.8 in WC static pressure. Table 1 is an example table showing a mapping of fan motor speeds, with a duty cycle of 50%, with air flow rates and static pressure, for a selected motor. Such a mapping can be obtained through laboratory testing and measurements.
At 202, the processor 104 can operate the recirculation air blower 128 at a first initial speed to guide recirculation air from an interior space to flow to the first side of the heat exchanger core 130. As described above, the processor 104, via fan motor controller 108, can control the recirculation air blower 128 to guide recirculation air from the recirculation air inlet 118 to the recirculation air chamber 124 and the first face 140a of the heat exchanger core 130.
Operation of the fan motor 134 at the first initial speed can be set when power is initially provided to the recirculation air blower 128. One or more switches or pushbuttons or the processor 104 can provide the first initial speed and power to the recirculation air blower 128. For example, a first switch can provide the first initial speed and a second switch can provide power to the recirculation air blower 128. In another example, a single switch can provide both the first initial speed and power to the recirculation air blower 128.
The one or more switches or pushbuttons can be remote or local. The one or more switches or pushbuttons can be manually or automatically controlled. In some examples, the one or more switches or pushbuttons providing the first initial speed can indicate speeds such as Low, Medium, Medium-High, and High. The processor 104 can adjust the fan motor controller 108 to operate at a duty cycle and a fan motor speed, based on a look up table, such as Table 1. For example, the processor 104 can adjust the fan motor controller 108 to generate an air flow rate of about 25 CFM at 0.8 in WC static pressure.
Operation of the fan motor 134 of the recirculation air blower 128 guides recirculation air from an interior space to flow to the first side of the heat exchanger core 130. As described above, the processor 104, via fan motor controller 108, can control the recirculation air blower 128 to guide recirculation air from the recirculation air inlet 118 to the recirculation air chamber 124 and the first face 140a of the heat exchanger core 130.
At 204, the recirculation air can be guided from the first side of the heat exchanger core 130 to be expelled outside of the interior space. Recirculation air in the first side of the heat exchanger core can travel to the first face 140b and the recirculation air outlet 138 to exit the apparatus 100.
At 206, the processor 104 can operate the fresh air blower 126 at a second initial speed to guide fresh air to flow to the second side of the heat exchanger core 130. As described above, the processor 104, via fan motor controller 106, can control the fresh air blower 126 to guide fresh air from the fresh air inlet 116 to the fresh air chamber 122 and the third face 140c of the heat exchanger core 130.
Operation of the fan motor 132 at the second initial speed can be set when power is initially provided to the fresh air blower 126. One or more switches or pushbuttons or the processor 104 can provide the second initial speed and power to the fresh air blower 126. Furthermore, the one or more switches or pushbuttons providing the second initial speed and power to the fresh air blower 126 can be the same switches or pushbuttons that provide the first initial speed and power to the recirculation air blower 128. For example, a single switch can provide an initial speed as both the first initial speed to the recirculation air blower 128 and the second initial speed to the fresh air blower 126. In another example, a first switch can provide power to the fresh air blower 126 and a second switch can provide power to the recirculation air blower 128.
Similar to the switches or pushbuttons for the recirculation air blower 128, the switches or pushbuttons for the fresh air blower 126 can be remote or local and manually or automatically controlled. The switches or pushbuttons providing the second initial speed can indicate speeds such as Low, Medium, Medium-High, and High. The processor 104 can adjust the fan motor controller 106 to operate at a duty cycle and a fan motor speed, based on a look up table, such as Table 1. The look up table for the fresh air blower 126 can be the same as, or a separate look up table for the recirculation air blower 128.
Operation of the fan motor 132 of the fresh air blower 126 guides fresh air to flow to the second side of the heat exchanger core 130. As described above, the processor 104, via fan motor controller 106, can control the fresh air blower 126 to guide fresh air from the fresh air inlet 116 to the fresh air chamber 122 and the third face 140c of the heat exchanger core 130.
At 208, the fresh air can be guided from the second side of the heat exchanger core 130 to be delivered to the interior space. Fresh air in the second side of the heat exchanger core can travel to the fourth face 140d to exit the HRV/ERV unit.
At 210, the sensor 110 can measure a pressure in the first side and the second side of the heat exchanger core 130 and generate an output indicative of the pressure difference between the first and second sides of the heat exchanger core 130.
At 212, the processor 104 can receive the output of the sensor 110 and determine whether the pressure difference is substantially zero, that is, whether the system is balanced. In some examples, the processor 104 can receive pressure measurements from the sensor 110 every 30 seconds. The processor 104 can determine that the system is balanced when the differential pressure is substantially zero. For example, a differential pressure of about +/−5 mbar can be considered substantially zero.
In some examples, the processor 104 can determine whether the system is balanced only in response to stable measurements from the sensor 110. Measurements can vary after the apparatus 100 is initially powered, or after any other operating changes to the apparatus 100. The processor 104 can determine that the apparatus 100 has stabilized when the measurements remain substantially unchanged for a pre-determined time duration. The time duration for stabilization can be determined through laboratory testing. For example, laboratory testing can determine that the system response time for a change in motor speed to propagate through the heat exchanger core 130 and the ductwork, can be in the order of minutes. Accordingly, the processor 104 can determine that the apparatus has stabilized when the measurements remain substantially unchanged for about five minutes.
If at 210 the processor 104 determines that the system is unbalanced, that is, the pressure difference is substantially non-zero, the method can proceed to 214. At 214, the processor 104 can determine whether to adjust the fresh air blower 126 and/or the recirculation air blower 128 to reduce a difference in pressure in the first side and the second side of the heat exchanger core 130.
In some examples, in order to determine whether to adjust the fresh air blower 126 and/or the recirculation air blower 128, the processor 104 can designate each of the recirculation air blower 128 and the fresh air blower 126 as a leader or follower based on the pressure measurements obtained from sensor 110 at 210. That is, the processor 104 can determine whether to operate: (i) the recirculation air blower 128 as the leader and the fresh air blower 126 as the follower, or (ii) the fresh air blower 126 as the leader and the recirculation air blower 128 as the follower.
If the pressure in the second side of the heat exchanger core 130, that is, the pressure from the fresh air, is greater than the pressure in the first side of the heat exchanger core 130, that is, the pressure from the recirculation air, then the pressure difference is positive and the processor 104 can operate the fan motor 132 of the fresh air blower 126 as the leader and the fan motor 134 of the recirculation air blower 128 as the follower. Alternatively, if the pressure in the first side of the heat exchanger core 130, that is the pressure from the recirculation air, is greater than the pressure in the second side of the heat exchanger core 130, that is, the pressure from the fresh air, then the pressure difference is negative and the processor 104 can operate the fan motor 134 of the recirculation air blower 128 as the leader and the fan motor 132 of the fresh air blower 126 as the follower.
The processor 104 can attempt to reduce the difference in pressure in the first side and the second side of the heat exchanger core 130, that is, equalize the pressure in the first and second sides of the heat exchanger core 130, by adjusting either the duty cycle/fan motor speed of the leader, the follower, or both the leader and follower. That is, the processor 104 can adjust the duty cycle of the leader, the fan motor speed of the leader, both the duty cycle and the fan motor speed of the leader, the duty cycle of the follower, the fan motor speed of the follower, both the duty cycle and the fan motor speed of the follower, or any combination of the same leader and the follower. When the processor 104 adjusts the leader, the processor 104 reduces the duty cycle/fan motor speed of the leader. When the processor 104 adjusts the follower, the processor 104 increases the duty cycle/fan motor speed of the follower.
The processor 104 can adjust the fan motor speeds of the leader and follower as long as their respective duty cycle is within a range of about 20% to about 86%.
In some examples, the processor 104 can adjust the fan speed of the follower relative to the fan speed of the leader. For example, the processor 104 can set the follower to generate an air flow rate that is the substantially equal to, or same as the air flow rate of the leader. In another example, the processor 104 can set the follower to generate an air flow rate that is the unequal to the air flow rate of the leader.
After the processor 104 adjusts at least one of the leader and the follower at 214, the method returns to 210 for the next pressure measurement. In some examples, the leader and/or follower can be incrementally adjusted followed by another differential pressure measurement at 210. That is, the processor 104 can further reduce the duty cycle/fan motor speed of the leader and/or further increase the duty cycle/fan motor speed of the follower after another differential pressure measurement that indicates that the system remains unbalanced.
For example, the processor 104, via fan motor controller 106, can adjust the air flow rate of the leader until the pressure difference measured by the sensor 110 is substantially 0 Pa. Returning to the above example with analog voltage output range and maximum pressure differences, the processor 104 can adjust the speed of the fan motor of the leader until the analog voltage output of the sensor 110 is substantially 1400 mV.
If at 210 the processor 104 determines that the system is balanced, that is, the pressure difference is substantially zero, the method can proceed to 216. At 216, the processor 104 can continue operating the system as is. That is, the processor 104 continues to operate the fresh air blower 126 and the recirculation air blower 128 without adjustments to the duty cycles and/or fan motor speeds. After 216, the method can return to 210 for the next pressure measurement.
In some examples, the sensor 110 can include a first pressure sensor to measure pressure in the first side of the heat exchanger core 130 and a second pressure sensor to measure pressure in the second side of the heat exchanger core 130. Pressure measurements from each of the first pressure sensor and the second pressure sensor can be provided to the processor 104. The processor 104 can determine the difference between the pressure in the first side and the second side and control the fan motor controllers 106, 108 accordingly. However, such examples can be more complex with the additional sensor, the synchronization of the two pressure measurements, and the additional computation required of the processor 104 to determine the difference between two pressure measurements.
While the above description provides examples of one or more apparatuses or methods, it will be appreciated that other apparatuses or methods may be within the scope of the accompanying claims.
This application claims priority to U.S. Provisional Application No. 62/749,209 filed on Oct. 23, 2018, the entire contents of which are hereby incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62749209 | Oct 2018 | US |
