NO20230212A1 - Hybrid plug-and-play outdoor monoblock heat recovery ventilation (H-HRV) unit with closed and open-loop functionality modes, featuring a thermally isolated condenser room and a heat-exchanger & heat-pump compressor room with Venturi add-on compatibility - Google Patents

Description

Title

“Hybrid Heat Recovery Ventilation (H-HRV) Unit with Closed/Open-Loop Functionality, Optional Venturi Module add-on, and Thermally Isolated Rooms" - This invention is a plug-and-play outdoor monoblock HRV unit that features closed and open-loop functionality modes. It includes a thermally isolated condenser room as well as a thermally isolated heat-exchanger & heat-pump compressor room. An optional add-on Venturi module is also compatible with the unit, allowing for reduced power consumption during operation. The Venturi module can function as a standalone cooler/ventilator in tropical/warm climates or as an add-on for an HVAC system with the intention of lowering fan power consumption using wind.

Purpose of the invention

The purpose of the invention is to reduce the initial cost as well as the total life cycle cost for a HVAC unit with simplifications and innovation.

The invention is a hybrid heat recovery ventilator with closed- and open-loop capability, mounted in monoblock design outdoor with a thermally isolated “condenser room” (during heating mode where air entering building is heated, during cooling mode the room is technically the “evaporator room”) and thermally isolated heat exchanger & heat-pump compressor room. Invention is in “plug & play” configuration meaning it can be easy installed with little to no need of certified personnel to help saving a lot of cost for the user. The invention also include the add-on Venturi module which is a Venturi structure that is able to create a low pressure area at the outlet and can replace the need of running the exhaust fan partially or completely, depending on the wind conditions. Venturi add-on module is a separate invention but included in the “package” as it is compatible with the unit and specifically created for HVAC use, it will have its own independent patent demand.

The initial cost can be reduced significantly with its “plug & play” design which simplify the installation, reducing needed time and qualification for installment and therefore the cost. To place a HVAC unit which has a heat pump, one typically need a qualified heat pump technician due to the need of fitting refrigerant lines and/or fill refrigerant into system. Most refrigerants today are governed by strict regulation both in term of safety, health, and emissions. Having a “plug & play” complete monoblock solution outdoor opens up the installation to anyone as the refrigerant circuit comes preinstalled ready to use, “plug & play”. For smaller units made for apartments, smaller houses etc. one can also reduce the need of an electrician as they are able to deliver heating/cooling needs with only around 1000 W to 1500 W of electrical power input. In this region regulations in most countries allow the unit to be plugged directly into a power outlet without having an electrician to create a new dedicated electrical power circuit from the fuse box, which will decrease the total investment cost for any homeowner to invest in greener options as one can eliminate this and utilize already existing infrastructure.

By making the invention compatible with an optional Venturi add-on module we are able to also reduce operational cost as one can use wind to drive the ventilation (air flow) through the building (in openloop) and unit (in open- and closed-loop). This add-on can be very beneficial for example at coastal cities which typically have good exposure to wind. The wind velocities needed to create low pressure regions sufficient to move a decent amount of air are usually low, especially for an engineered shape as the Venturi, an example being the effect even a small wind has on chimneys connected to a fireplace. The Venturi structure is also a product that can be very useful as a stand-alone solution mounted at buildings located in warmer climate and only is looking for ventilation for cooling (flow of air). But by using the Venturi with the HRV (heat recovery ventilator) unit we will be able to reduce the energy need of the unit a lot as we can reduce the fan power required which for a HVAC unit with ducts can be hundreds of watts depending on the building size. A venturi is an effect but also commonly used for a geometry that experience this effect which state that when a fluid flow through a constriction/choke of pipe its speed will increase, and its pressure will decrease. This effect has its origin from the mass and energy conservation laws which is practically described by Bernoulli’s equation.

The unit itself is already by design placed in an area of extreme efficiency in terms of heating and cooling solutions/products. Using a heat pump, we are able to extract 2 to 5 times the amount of heat energy than electrical energy put into it (the efficiency main variable is the temperature gap between delivered fluid temperature (outlet) and incoming fluid temperature (inlet), the warmer incoming air (heating mode) is into a heat pump the more efficient it can operate) which in itself is considered a very efficient method of heating and cooling a building. Heat pumps are usually a stand-alone system where it extract/inject energy from/to the cold/warm outdoor air directly which then is injected/extracted to/from the indoor air, heating/cooling it. They do not move fresh air from outdoor, heat it and move it indoor but rather reheats the indoor air continuously in a loop, having the indoor as a closed system separated from the outdoor with only energy crossing the boundary not mass. They are very popular and have many advantages over the alternatives (resistive heaters, bio-ovens etc.). The solutions closedloop mode operates in a similar way, looping the indoor air reheating it through the HRV unit.

Heat pumps / closed-loop mode works well in older homes which has by default some air leakage. This leakage is the house “natural” ventilation system and have been the norm, this is the reason one rarely had to think too much about having an actual ventilation system installed. This “natural” ventilation system works in the following way. Explained in a simplified example, let’s say one have three floors. In reality this can take place in a single floor, two floor and so on. As a stand-alone heat pump heats the air at the middle floor this air will start rising due to its higher temperature than the surrounding air (buoyancy differences). As this continue it will be a higher concentration of air in the top of middle floor compared to the bottom as the heat pump suck in “cold” air from floor level, heats it and it moves by buoyancy differences to the roof. Concentration of air particles is the definition of pressure. Meaning we will have a high pressure at the top of floor and low pressure at bottom of the floor. This pressure difference will start pulling air in from the bottom floor (1st) due to low pressure by the floor and pushing air out of the roof to the top floor (2nd) due to the high pressure by the roof. In real buildings these floors can be for example be the basement and the attic. Basements pull cold air into the building through the walls and the attic push warm air out into the ambient environment. This effect is enhanced during windy conditions as wind can create low pressure regions on the outside of the roof pulling the “high pressure” from the inside out.

The problem with stand-alone heat pump systems / closed-loop mode is that today’s building codes are much stricter in regard to air leakage and try to keep leakage to a minimum. The reason being to better keep homes warm/cold using less energy, leakage being one of the major energy wasters (inefficiencies). As well as it has been a boom in making older homes more airtight, with huge amounts of money and resources being used on services as thermo-scanning/”BlowerDoor-testing” to map air leakages and remove them. Uncontrolled air leakage is one of the largest contributors to energy loss in residential buildings as one has to continuously warm/cool buildings to keep them comfortable for occupants. Although sealing buildings are a good method energy wise, it is problematic in regard to air quality. Airtight buildings without ventilation suffer from poor air quality which in turn can cause health issues, poor air quality reduce life quality substantially, from headaches to asthma. Having good ventilation is also absolutely necessary for buildings which is located in Radon gas exposed areas, which over time can cause lung cancer for occupants. This is why ventilation is absolutely necessary to be added when the natural air leakages are removed. But adding ventilation defeats the whole purpose of sealing the building as one now is artificially adding air leakages back again loosing energy as the heat from the indoor air is not recovered. This is where the invention finds its place. By both being able to provide closed-loop capability which most likely will be to dominating mode for older homes where natural ventilation (non-airtight buildings) exist as well as open-loop capability which most likely will be the dominating mode for newer homes / upgraded homes, we are able to switch between the modes and from air quality readings find the optimal operation point where energy and air quality is kept highest. For example, during nighttime one might choose to operate open-loop as this will provide the occupants sleeping with high quality air, the energy “penalty” being less significant due to the lower electricity cost, while during the day when the home is empty one can operate closed-cycle/sleep-mode. The invention hybrid solution opens up too many operation modes.

The invention recommends having the low pressure air duct mounted by the floor with the purpose of creating a low-pressure region at the floor level able to counter-act this rising heat effect and pull the high rising warm air to floor level where occupants/consumers of the heat are located. This is depicted in figure 1. Having the suction side at floor level also will work as a sort of a filtration-system, pulling with it dust (heavier particles), hair etc. out of the room. A filter will be implemented at the suction connection port, at the indoor side for easy access.

The invention is also made to be mounted “outdoor”. The reasoning for this is to accommodate the design for the possibility of using hydrocarbon refrigerants which with its low global warming potential is a much more ecofriendly option that the common refrigerants used as well as often having a higher efficiency in a heat pump cycle. New regulations as the “EN 378-1:2016+A1:2020” open up for more widespread use of hydrocarbon refrigerants as propane but they require extra safety measures due to their fire-hazard potential, having the whole refrigerant line with its component outdoor fulfill requirements reducing the complication of an indoor solution. Another benefit of having the unit mounted outdoor is that it does not use indoor space as well as it will reduce the noise experienced inside which for HVAC solutions can be problematic.

The add-on venturi module which can be beneficial for open-loop cycle operation for buildings located at windy areas (usually costal cities) can also serve extra purposes and be connected to replace for example kitchen fan etc. The Venturi is planned to be made up from a 360 disc type design with guide fins, able to produce low pressure / suction from any wind direction. Typically mounting location for module can be at the ridge of the roof or any other places where it is most exposed to free air flow.

Having a lower initial cost which is a biproduct of the simplicity of installation and design on such a setup would make it possible for more people to do the investment as well as it would make it easier for such a setup to return a positive net present value. It also enables people in remote places to invest in this technology as a certified heat pump technician is not necessary nor for the smaller units, a certified electrician, and the installment of the unit itself can be done by anyone. This also include the air ducts which has no regulations on qualification of installment contradictory to for example liquid (water) based heat pump solutions which need a plumber to connect/install the liquid carrying heat pipes around the homes (waterborne heating).

Background for the invention and its working in detail

This invention relates to the whole "Plug & play" hybrid outdoor monoblock heat recovery ventilation unit with closed- and open-loop functionality modes with a thermally isolated "condenser" room and thermally isolated heat-exchanger & heat-pump compressor room and compatibility with an optional add-on Venturi module for reduced power usage during operation.”, it also included is the components necessary to move air into/from the building through existing/made air vents as well as the filter with its components.

A heat recovery unit is a known component but is not very common nor standardized. Often, they are made up by only a heat exchanger and is usually sold as components which one arrange in a certain way indoor to make up a heat recovery unit. Outdoor monoblock units for residential use does not exist and the only monoblock solutions that does exist are made up of only a heat exchanger and usually made for commercial/industrial use.

The invention uses a heat recovery setup where one in open-loop cycle flows the warm existing indoor air which is sucked out of the building by the airducts located at floor level through a heat exchanger where it exchanges its heat with the fresh outdoor air stream which is sucked directly from the surrounding air and is to replace the warm air removed from the building. When maximum heat exchange has been achieved for a given reasonable heat exchanger size (further described below), the now slightly heated outdoor air goes to the heat pump circuit which is located in series with the heat exchanger. The heat pump circuit can move large amount of heat energy for small temperature gaps but require mechanical energy in the form of a compressor to run unlike the heat exchanger which needs no mechanical energy directly. It is the heat pump that remove “all” the excess usable energy from the indoor air stream that the heat exchanger was unable to absorb and move it to the new outdoor air stream that already has been warmed up slightly by the heat exchanger. After the heat pump the indoor air stream, now very cold, is vented to the surrounding air which for our invention is located either on a outlet directly from the monoblock unit or if the add-on is installed it will be located at the Venturi structure (see figure 1). The outdoor air stream, now at room temperature or higher (for heating mode), enters the building warming the occupants/consumers, for example humans or other consumers as a water heater heat pump with fresh air. The Venturi which will be described in further details below is a geometrical shape that induce the Venturi effect, a low-pressure at a “choke” point, when wind blow through it which can be used to pull air through the unit. Therefore, reducing the power consumption partially or completely depending on the wind conditions.

The invention uses a heat delivery configuration where one in the closed-loop cycle flow the warm existing indoor air which is sucked out of the buildings indoor by the airducts located at floor level through the circulation fan, circulation fan is only used for closed-loop cycle and serve the purpose of circulating the indoor air through the unit’s heat-pump. Afterward the flow moves directly through the heat pump circuit which is in series with the circulating fan and its temperature is lifted enough to provide the users with the target indoor temperature (in heating mode) through the condenser and the flow is redirected back into the building where the flow begin the loop again, performing the close cycle.

The heat-exchanger is in “full” use only in open-loop mode meaning that in open-loop mode it operate as designed, moving heat from the “used” indoor flow to the “new/fresh” outdoor flow. In close-loop mode however, the heat-exchanger is not directly in use. Outdoor flow is still directed through it as for open-loop cycle on one of the sides (one inlet & one outlet), but the other side is not used in closed-loop mode, meaning the heat-exchanger does not exchange heat between flows. The purpose of still running the outdoor air through the heat-exchanger still is to cool the compressor / absorb the waste heat from the compressor. Providing some “extra” heat to the flow before the heat-pump evaporator (heating mode), while also keeping the compressor from overheating. Heat-exchanger is a great method of recover heat energy as it requires no compressor, just a component to make both air stream flow over the material separating them. The convergence of the temperature streams will affect both the heat transportation effects and decrease the overall heat transport. Therefore, a heat exchanger is a great “tool” to use before a heat pump when the fluids streams, the warm air from the building and the cold air from outdoor, can meet directly as they have a large temperature difference. When a given temperature convergence has been achieved, which mostly rely on the size of the heat exchanger, then the flow can be sent to the next step.

A heat pump is a general term used for products/solutions which use a refrigerant fluid to move heat from an evaporator to a condenser. The first classification that can be made for heat pump is to classify it by the need of a compressor. The heat pump type that does not utilize a compressor is known as an absorption heat pump, the type that utilize a compressor is known as a compression heat pump, this invention is classified in the latter. This products/solutions in this group typically all have four components in common which is the evaporator, condenser, compressor, and an expansion valve. The heat pumps job is to move or “pump” heat, in heating mode the heat is moved from a place of low temperature to a place of high temperature typically from outdoor to indoor. It can also be used in cooling mode where heat is moved from a place of high temperature to a place of low temperature and is then usually referred to an “air conditioning unit” rather than a heat pump (AC is not able to heat, only cool while a heat pump is able to do both). The heat pump is able to move this heat by utilizing a refrigerant. The refrigerant is decided so that for its given operating condition the refrigerant will turn into gaseous form inside the evaporator and into liquids form inside the condenser for the given temperature it is to create. It is this phase change that is able to extract/insert so much heat and makes a heat pump so efficient.

The operation cycle of the heat pump in heating mode begins when the refrigerant in gaseous form is compressed to a higher pressure through the compressor. Exiting the compressor, the refrigerant which still is in its gaseous form has now been given a higher pressure and a higher temperature. The temperature increase is a product of the pressure increase, they are correlated through the gas laws (see “ideal gas law”). The next step in the cycle is for the refrigerant to move through the inside of the condenser where the refrigerant with its higher temperature will transport heat to the colder medium that is surrounding the outside of the condenser. It is during this cooling of the refrigerant that it will change into liquidous form. Exiting the condenser, the refrigerant is now in liquidous form, but the high pressure still remains. The next step in the cycle is for the refrigerant to move through an expansion valve where the refrigerant pressure drops from a high pressure to a low pressure. Exiting the expansion valve the refrigerant is still in liquidous form but has been given a lowered pressure and a lowered temperature (again a corelated relationship through the gas laws). The next step is in the cycle is for the refrigerant to move through the inside of the evaporator where the refrigerant with its low temperature will absorb heat from the warmer medium surrounding the outside of the evaporator. It is during this heating of the refrigerant that it will change into gaseous form. Now the operational cycle repeat. A heat pump running in cooling mode works exactly the same as a heat pump in heating mode only running the compressor and therefore the cycle in the opposite direction which in practice will make the condenser the new evaporator and evaporator the new condenser.

A heat pump using the cycle described in the paragraph above is able to extract/convert approximately 2 to 5 times more energy in the form of heat than the mechanical energy it uses to run the compressor (the efficiency main variable is the temperature gap between delivered fluid temperature (outlet) and incoming fluid temperature (inlet), the warmer incoming air is to a heat pump the more efficient it can operate). For comparison a typical electrical heater also known as a resistance heater will be able to maximum extract/convert the same amount of heat energy as the electrical energy used by it.

As for the more common components found in HVAC solutions, the heat exchanger and the heat pump have been discussed. These are commonly found but not in series as the invention propose, especially in a complete “plug & play” outdoor unit with separate thermal isolated rooms. The only necessary input energy to the solution/unit that has been discussed is the compressor necessary to run heat pump cycle. The power to actually move the air flows have been ignored for now.

To be able to suck air through the unit itself with its two passes through the heat-exchanger, one pass through the condenser and one pass through the evaporator as well as the air ducting system the unit is to be connected to and the rooms itself one need to have a relative high potential difference. This is one of the major problems with heat recovery units, heat pumps and ventilation in general (HVAC), creating a pressure difference to move the fluids. The common option which is used in all if not every HVAC solution/product is to purely rely on fans. Fans are a mechanical component which has a certain geometry on its blades which makes pulls air through it when rotating. This pulling of air makes a low pressure “behind” the fan while a high pressure in “front” of the fan. The low-pressure region is low enough to pull the needed flow rate to the system, having a given needed pressure difference to the entry point (ambient entry having a higher pressure than the low-pressure region of the fan), while the high-pressure region being high enough to make the same needed pressure difference between the high-pressure area and the exit point (ambient exit having a lower pressure than the high-pressure region of the fan). Fans require a lot of energy which decrease the overall efficiency of the HVAC system/solution and therefore increasing its operational cost which in turn increase life cycle cost making the advantage of making the investment lower. This is where the inventions Venturi module find its place.

A “venturi” is a vague term used to categorize a geometrical shape that induce the Venturi effect. The Venturi effect is the reduction of fluid pressure that happens when a fluid velocity is made to increase through a narrow pass / constriction / choke. It is most defined in constriction/reducers in pipes but can be found from everything from tall buildings with a narrow pass between them to the underbody of a formula 1 car where the air flow find itself in a constricted space and therefore must speed up to be able to keep the mass flow the same which in turn decrease the pressure. The Venturi effect is a product of the energy- and mass-conservation laws and is practically described by Bernoulli’s law for incompressible fluids (the compressibility properties of air is assumed to have minimal/negligible effect for velocities smaller than 1/3 of its speed of sound). Having a Venturi at the roof of a building or another place where it is exposed to free moving wind, we can create a low-pressure which we can connect to our unit to pull the air through. A Venturi is a powerful geometry and has the ability to produce several kPa of “vacuum” by relatively slow-moving wind speed. Most cities/population and therefore buildings especially in the Nordic countries are located at the coastline. The coastline during winter is subjected to high winds with almost none “wind free” days. The reason is the cold inland climate and the warm ocean which with its temperature difference makes a pressure difference which in turn create wind. These are the perfect condition to mount a Venturi which are able to extract the “energy” of these wind speed. In this way we are able to extract wind energy directly to use in our invention instead of using a wind turbine to for example produce energy to then run a fan, which is much less efficient and cost much more to implement.

When wind move through the 360 degree disc Venturi shape it will create a low-pressure area at the intake of the Venturi located at the bottom (see figure) due to its shape and narrow passage. The shape itself makes the airflow partially/completely separate from the “bottom” of the Venturi just at the point of where it is connected to the unit depending on the wind velocity and shape. This separation also helps to create a low-pressure as air is hindered to fill up the space. This “separational effect” (known as stalling when happening over an airfoil of an aircraft) is not a part of the Venturi effect but is also a way to produce low-pressure and with the combination with the Venturi effect, a low-pressure region at the “exit point” of the unit piping can be maintained for even low wind velocities. The low-pressure region pull air through the unit, this air is drawn out through the vent located in the Venturi, “exit point”, which then is carried away by the wind. This carried away air must have replaced with “new air” this will come into the unit through the “entry points”. It is this carrying away of the unit air that maintain the lowpressure and pulls new air into the unit. The entry points differ from open-loop to closed-loop mode. In open-loop the Venturi (or exhaust fan if the exhaust fan is used) must pull air through the whole unit as well as the ventilation ducting indoor. It pulls the air the whole way from the “Ambient air” intake as seen in figure 1. For the closed-loop the Venturi (or exhaust fan if it is used) has a smaller job only needing to pull air through the unit, not the ventilation ducts as well. The job of pulling air through the ventilation ducting is left for the circulating fan which only is used for closed-loop mode. Circulating fan also need to pull air through unit. The venturi has a 360-degree disc/circle shape with guiding blades, being able to work for any wind direction.

As described in this section the invention is built on existing principles/inventions but combine them in a unique way to make it function as the product it is. It is made to be a complete outdoor unit ready to go, “plug & play” designed. It is made to avoid the need of a qualified heat pump technician by having everything in an outdoor monoblock, it also accommodates for the potential use of hydrocarbon refrigerants by having a thermally isolated condenser room and thermally isolated heat-exchanger & compressor room which makes it able to be mounted outdoor. The compressor is to be placed inside the thermally isolated heat exchanger room for a potentially increase in efficiency further as the waste heat from the compressor can be absorbed by the heat-exchanger while holding the temperature below the maximum operating temperature. For the smaller variant for apartments and small houses one can also eliminate the need for a qualified electrician to create a new dedicated electrical power circuit for the heat pump itself. This is possible as we are able to meet the heating/cooling demand with an input of 1000 to 1500 W which regulation in most European countries allow to be powered directly with an existing earthed power socket.

Note that the invention although a heat recovery ventilator (HRV) is also perfectly capable of cooling building as well by only reversing the heat-pump cycle which is done using a reverse valve which most heat-pump systems come preinstalled with. Reversing the cycle will make the thermally isolated condenser room into a thermally isolated evaporator room, where flow is cooled down (extracted energy from) instead of heated (injected energy too).The reversing valve effectively make the evaporator the condenser and vice versa. The invention includes both heating and cooling, perfectly capable of operate in either cold climate as well as in warm climates.

Also note that the invention also opens up for moving the heat-pump compressor out of the thermally isolated heat-exchanger & heat-pump compressor room. There is nothing in the way of moving the compressor out of the thermally isolated room with the exception of waste heat from the compressor body escaping to the environment instead of being absorbed by the heat-exchanger.

Summary

The hybrid heat recovery ventilation (H-HRV) unit is a plug-and-play outdoor monoblock system with closed and open-loop functionality modes, featuring a thermally isolated condenser room and a thermally isolated heat-exchanger and heat-pump compressor room. The unit is compatible with an optional add-on Venturi module that reduces power consumption during operation. The Venturi module can be used as a standalone cooler/ventilator in tropical/warm climates or as an add-on for an HVAC system, reducing fan power consumption using wind. The invention provides an energy-efficient ventilation and air conditioning system that operates in both closed and open-loop modes, with the primary application being indoor air quality, temperature control, and energy savings for residential and commercial buildings. The H-HRV and Venturi unit have their own independent patent claim, with Figure 1 recommended for publication with the summary.

Description of the drawing/figure with explanation of the components/modes of the invention

Figure 1 which is the only figure provided with this patent application shows the whole unit and how it is to be connected to a building. The figure also shows us how the add-on Venturi module is to be connected to the unit if installed. Further in details is the working of the whole unit, how the different modes operate and what airflow goes where when selected mode is activated. The walkthrough of this section will go through the invention during heating mode, meaning that the heat recovery unit purpose is to heat the occupants/components indoor. Both open-cycle (loop) and closed-cycle (loop) mode is to be described.

Beginning with open-cycle. In open-cycle mode we let in ambient air through intake (14) which is located at the outdoor monoblock unit body (26). This inlet air flow has been given symbol [A0] which denote the beginning of the open-cycle. The open-cycle mode consists of a single connected flow from inlet to outlet flow and is denoted by the "o" subscript. The flow then passes through the inlet choke valve (13) which can be used to choke inlet. From here the flow move toward the thermally isolated heat-exchanger & heat-pump compressor room (11) into the heat-exchanger (10) at [Bo], moving through the heat-exchanger absorbing the heat from the exhausted indoor air which is moving from [Ho] to [Io]. The flow now heated slightly from the heat-exchange comes out of the heat-exchanger at [Co]. From the drawing it can be hard to see which valves open and which ones are closed, but as written in the figure itself, all valves are closed except the ones that ensure that the alphabetical open-cycle flow with the “o” subscriptions notation is connected. This means that for us in open-loop mode the valves laying in the path between [Co] and [Do] are open, as well as all other valves with “o” subscriptions paths running through them (given they are in alphabetical order. Understanding this we know the flow moves through the 3-way valve (8) and toward the thermally isolated “condenser” room (16) into the heatpump condenser (15). Here the flow is heated further all the way to the “target” temperature of the interior of the building. Leaving the condenser at [Eo] the flow moves toward the building through the air vent connecting the unit to the indoor with connecting point at (22) [Fo]. This connection points have a flange (22 & 4) which can be connected to air ducts (24 & 1) as illustrated in Figure 1. After the flow which is now warmed fresh air has entered the upper air duct (24) (high pressure duct), it will move through the room(s) warming occupants/consumers of heat toward the lower air duct (1) (low pressure duct) [Go]. The flow is so pulled through a filter (5) which is easily accessible from indoors and hinder dust/particles being drawn into the unit with the airflow. Moving through the filter the flow encounter a new 3-way valve (6) where by using the methodology learned before we know the valve will only be open between [Go] and [Ho]. [Ho] is located inside the thermally isolated heat-exchanger & heat-pump compressor room (11) at one of the intakes to the heat-exchanger (10). This is the “exhaust” inlet where the flow which now is “used” warm air from the indoor can enter the heat-exchanger and exchange its heat with the fresh airflow moving from [Bo] to [Co]. The flow now cooled down slightly exits the heatexchanger through the “exhaust” outlet at [Io] and move toward the heat-pump evaporator (18) at [Jo]. In the evaporator the flow which still has significantly higher temperature than the ambient air (contain more heat) is cooled down as the evaporator extract the rest of its “useful” heat. This heat is the heat that is injected to the flow moving from [Do] to [Eo] in the condenser (15) by the heat-pump cycle (12, 15, 17 & 18). Exiting the evaporator at [Ko] the flow moves through the exhaust fan (19). This fan is always on if the Venturi add-on module (21) is not installed, if the add-on is installed the fan can be partially reduced or completely off depending on wind condition and the Venturis ability. The exhaust fan is the only fan used for open-loop mode with the circulating fan (7) only being reserved for closedloop mode. It is the exhaust fan or the Venturi or a combination of both that pulls the air all the way from the inlet at (14) through the whole unit, airducts and building path described above. After the exhaust fan the air will move through the outlet choke valve (20) which can be used to choke outlet flow. Depending on if the add-on Venturi module has been installed or not, the outlet of the flow into the ambient air will be either at [Lo] which is an outlet compatible flange at the body of the monoblock or the outlet will be in the Venturi modules center (21) at [(Lo)].

For the close-cycle flow we have two different flows meaning that the flow is no longer a connected single flow, therefore the closed flow with subscript “c” also have numbers to identify them. This numbers 1 and 2 denote if the flow is the “outdoor ambient flow” or the “circulating indoor flow” respectively. Beginning with the outdoor ambient flow beginning at [A1c] at the air intake (14) located at the monoblock shell (26). The air proceed through the intake choke valve (13) and then to the thermally isolated heat-exchanger & heat-pump compressor room (11) to the inlet of the heat-exchanger (10) at [B1c]. We notice that the flow so far follows the exact route of the open-loop and although both flow through the heat-exchanger they have different purpose in the heat-exchanger. For the open-loop we exchanged heat with the exhausted indoor air, while now for the closed loop the flow’s purpose from [B1c] to [C1c] is to keep the inside of the thermally isolated heat-exchanger & heat-pump compressor room (11) cold, absorbing the waste heat from the heat-pump compressor (12). The other path through the heat-exchanger ([Ho] to [Io]) is not in use during the close cycle mode. After passing through the heat-exchanger and exiting at [C1c] the flow has absorbed the waste heat from the compressor and move through valve (9) toward the entrance of the heat-pump evaporator (18) at [D1c]. This flows purpose (“outdoor ambient flow” -> 1) is to bring heat to the heat-pump cycle, and its heat is absorbed as it passes through the evaporator. Exiting the evaporator at [E1c] the flow move toward the exhaust fan (19) which as with the open-loop mode might be off, on or reduced depending if the Venturi add-on module (21) is fitted and the wind conditions are favorable. The difference from the open-loop is that the exhaust fan only pull air through the unit from the air intake (14) to the outlet [F1c] or [(F1c)], while for the open-loop the exhaust fan pull air through the whole “system” meaning the building, air ducts as well as the unit. After exiting the exhaust fan (19) the flow is moved through the outlet choke valve (20). If the Venturi add-on module (21) is fitted the final outlet will be at [(F1c)]. If it is not fitted the outlet will be located at the monoblock body (26) directly at [F1c]. That is the whole flow path of the “outdoor ambient flow” identified with number 1 which has the purpose of delivering heat to the heat-pump cycle described. The next flow to describe is the “circulating indoor flow” identified with the number 2 which purpose is to move through the interior of the building heating up the occupants/consumers and circulate back through the unit absorbing energy from the condenser before repeating the steps (closed cycle). This mode does not provide fresh air but in turn reduce energy consumption. The “circulating indoor flow” begin at [A2c] which is located at the intake of the circulating fan (7). This fan’s purpose is to circulate the flow through the unit, through the heat-pump condenser (15), the air ducts and through the building. The fan is ”closed” feeding itself and is only active for the closed-cycle mode. After moving through the fan, the flow move towards the 3-way valve (8). Using the methodology used for open-loop we understand that the valve is opened so the flow can move freely toward its next point located at [B2c] in the thermally isolated “condenser” room (16) at the entrance to the heat-pump condenser (15). Here the flow is injected with the heat that previously was absorbed from the “outdoor ambient flow” moving from [D1c] to [E1c] and its temperature is raised to the target temperature before exiting the condenser at [C2c]. The next step for the flow is the connecting point (22) located indoors at [D2c] the entrance to the upper airduct (24) (high pressure duct). Here the now heated flow move through the interior of the building from the ceiling (23) toward the floor (2) heating the occupants/consumers in between. As it approaches the floor it is “sucked” into the lower airduct (1) (low pressure airduct) at [E2c] before moving toward connecting point (4) and filter (5). The next step is the 3-way valve (6) where we see that the valve is opened so that the flow path between [E2c] and [A2c] is open, from here the cycle repeats itself circulating and reheating the “circulating indoor flow”.

Table 1 - Component list from drawing Figure 1 attached this application

Claims (4)

Patent claims

1. A heat recovery ventilator (HRV) unit with open-cycle and closed-cycle capabilities for heating, cooling, and ventilating indoor occupants and/or components, comprising: a) An outdoor monoblock unit body (26) with an air intake (14) for ambient air to enter, an air outlet "Lo/F1c" for exhaust air to exit which outlet connection is compatible with the optional add-on Venturi module (21) from claim 2, for reduced need of running the exhaust fan (19) partially or completely, and intruding air vents (4 & 22) for connecting the unit to the building's interior air ducts; b) A thermally isolated heat-exchanger room (11); c) A thermally isolated heat-pump "condenser" room (16); d) A heat-exchanger (10) for exchanging heat between the ambient air intake airflow and the exhausted indoor air flow (open-cycle); e) A compression heat-pump cycle consisting of e1) A heat-pump compressor (12) for compressing the refrigerant and generating heat; e2) A heat-pump condenser (15) for transferring the heat to the indoor air; e3) A heat-pump evaporator (18) for absorbing heat from the outdoor ambient air (closed-cycle) or the exhausted indoor air (open-cycle); and d4) an expansion valve (17) where the refrigerant expands; f) A circulating fan (7) for circulating the indoor air through the heat-pump condenser (15), the air ducts (1 & 24), and the building (only used for closed-cycle); g) An exhaust fan (19) for pulling the air through the heat-pump evaporator (18) and unit (26) (closed-cycle). For opencycle, the exhaust fan additionally needs to pull air through air ducts (1 & 24) and the building; h) A filter (5) for removing dust and particles from the airflow before it enters the monoblock unit; i) A plurality of valves (6, 8, 9, 13, 20) for controlling the flow of the air through the unit (26).

The heat recovery unit of claim 1, will open the following valves (6, 8, 13, 20) for the open-cycle operation mode so as the alphabetical open-cycle flow with the “o” subscriptions notation is connected, open-cycle mode consisting of one single connected flow. For open-cycle only the exhaust fan (19) is needed, if Venturi add-on module (21) from claim 2 is installed the exhaust fan power can be partially or completely removed. Heat-pump cycle (12, 15, 17, 18) operate as normal, either providing the indoor with heated or cooled flow. Heat-exchanger (10) exchanges heat between exhausted indoor flow moving from Ho to Io with the fresh incoming flow from the intake moving from Bo to Co.

The heat recovery unit of claim 1, will open the following valves (6, 8, 9, 13, 20) for the closedcycle operation mode so as the alphabetical closed-cycle flow with the “c” subscriptions notation is connected. The numbering 1 and 2 are used to identify the two different flows, 1 is used to identify the “outdoor ambient flow” from the intake (14) while 2 is used to identify the “indoor circulating flow” alternating between the unit (26) and interior of the building. Heatpump cycle (12, 15, 17, 18) operate as normal, either providing the indoor with heated or cooled flow. Heat-exchanger (10) do not exchange heat with flows but provide cooling inside the thermally isolated heat-exchanger room (11).

The heat recovery ventilator unit of claim 1, wherein the add-on Venturi module (21) is fitted, the airflow outlet is at [(Lo)].

The heat recovery ventilator unit of claim 1, wherein the add-on Venturi module (21) is not fitted, and the airflow outlet is at [Lo].

The heat recovery ventilator unit of claim 1, can heat or cool the interior of a building. The patent description and demands are written for “heating mode” to be consistent and to not make confusion for the reader as where components are located and what their name is. When the heat recovery ventilator unit work in cooling mode the heat-pump cycle is reversed (a->b->c->d to d->c->b->a) which makes the condenser (15) the new evaporator (18) and vice versa, most heat-pump systems come with reversibility ability as standard.

1.1 The heat recovery ventilator unit of claim 1, can have the compressor (12) for the heat pump cycle mounted inside the thermally isolated heat exchanger room (11) for less heat loss to the surrounding. Biased for heating mode, the cold incoming airstream absorbing “waste” heat from compressor.

1.2 The heat recovery ventilator unit of claim 1, does not require a thermally isolated room (11) for the heat-exchanger and/nor the heat-pump “condenser” and can also work without one, although some heat loss will occur.

1.3 The heat recovery ventilator unit of claim 1, can be made more compact only needing one hole into the building for the airduct instead of two as depicted in Figure 1.

2. Use of a Venturi module/structure, as depicted in Figure 1 (21), to create a low-pressure zone at the exit point of a ventilation system (example [(Lo/F1c)] as seen from Figure 1), thereby partially or completely replacing the need for fans (in claim 1 the module reduces the need of the exhaust fan (19) partially/completely when installed). The Venturi device (21) comprises two circular curved discs that are mounted at a distance from each other, with guiding blades positioned in between. Circular discs enable the structure to work in any wind direction. The curved circular discs are positioned in a parallel manner, with the guiding blades arranged in between them to direct the flow of fluid passing through the Venturi structure (21). The curved circular discs are designed to create a convergent section at the inlet of the device, which increases the fluid's velocity, followed by a divergent section that decreases the fluid's velocity, creating a low-pressure zone at the center of the device where the outlet of the standalone-/HVAC-system is to be connected (again looking at Figure 1 we see where the exhaust outlet [(Lo/F1c)] for the HVAC system described in claim 1 is to be connected to the Venturi module (21) to expose outlet to a low-pressure region). See Figure 1 attached this application for a more detailed look of the Venturi module itself as well as how it can be integrated/connected to a HVAC system as an add-on unit.

The Venturi module/structure can be used as a standalone system or incorporated with an HVAC system installed as an add-on module. By using the Venturi device to create a lowpressure zone, it is possible to achieve electrical-free ventilation for cooling in warm/tropical countries where use of standalone systems is ideal, or it can be used to reduce fan power consumption for HVAC systems. The Venturi device's versatile design and cost-effective operation make it a flexible and practical solution for ventilation and cooling needs in a variety of settings, from small residential structures to large commercial buildings, providing a natural and sustainable alternative to traditional ventilation systems that require electrical power. The positioning and connection of the Venturi device to the HVAC unit are depicted in Figure 1, which shows how the device is integrated into the HVAC system described in claim 1.

Overall, the use of the Venturi module/structure provides a cost-effective and efficient solution for creating a low-pressure zone, without the need for additional fans or other equipment. By creating a low-pressure zone at the exit point of a ventilation system, the Venturi device allows for the natural flow of air to move through the system, providing effective cooling and ventilation without the need for electrical power.

2.1 The Venturi module written in claim 2, can be mounted anywhere were it is exposed to wind.

2.2 The Venturi module written in claim 2, can be of smaller sizes ideal for small HVAC units or made at a large size made for large complex HVAC systems.

2.

3 The Venturi module written in claim 2, can be fitted with a wind turbine for power generation) which can be mounted within the main airflow line or inside the Venturi itself between the curved circular discs.

2.

4 The Venturi module written in claim 2, does not need to utilize the Venturi effect to make a lowpressure (suction). It also can partially or purely be a structure made to create partial/complete airflow separation; this is also a method of achieving low-pressure at exit point [(Lo/F1c)].

Example of a structure that would utilize this effect purely would be the shape we are left with if we were to remove the top half of the Venturi structure (21) seen in figure 1, this reverse ushape will be able to create a low-pressure at the exit point [(Lo/F1c)] but does not utilize the Venturi effect, rather a type of “airfoil effect” where the separated airflow creates a low pressure region along the whole center and down-stream foil/shape.