Indoor air cooling

Abstract

The invention concerns a building air cooling system that comprises a thermoelectric heat pump (10) with a cold plate (11) and a hot plate (12), an indoor heat exchanger (3) for indoor air at the cold plate (11), a water duct (8) at the hot plate (12), an entry water conduit (50) at the water entry (30) of the water duct (8) and an exit water conduit (51) at the water exit (31) thereof. The entry water conduit (50) is configured flow-capably to connect to a plumbing system (40, 41) of a building. The exit water conduit (51) is configured to dispose of heat from the indoor heat exchanger (3) towards an outdoor environment. A flow-influence device (34, 35, 36, 37, 38) that is configured to influence the flow through the water duct (8) and to do so in the entry water conduit (50), the water duct (8) or the exit water conduit (51). The invention also concerns a method for installing suchlike building air cooling systems. The invention further concerns a room air cooling unit that comprises a thermoelectric heat pump (10) in between a heat-conductive foam (3) and a water duct (8), which are fixedly connected with respect to each other.

Description

[0001] The invention concerns building air cooling systems. In context, a building is a house, office, factory, school, hospital, museum, church, railway station, ship or other dwelling. A building air cooling system according to the invention comprises at least one thermoelectric heat pump that includes a cold plate from which in operation as intended it transfers heat and that includes a hot plate to which in operation as intended it transfers heat. It also comprises at least one indoor heat exchanger that is thermally connected to the cold plate and that is configured in operation as intended to remove heat from the indoor air. Preferably, the indoor heat exchanger is thermally connected to the cold plate such that heat transfer is fully caused by temperature difference, that is, without mechanical assistance such as a pump that circulates a heat transport fluid between the indoor heat exchanger and the cold plate.

[0002] Suitable thermoelectric heat pumps of various design can be obtained commercially. Examples of their construction are described in US2005 / 0016575A1, for instance. Perovskite-material components may become usable too.

[0003] Such a building air cooling system is the cooling, heating and ventilating system that is described in patent application KR2012035308A. By means of an indoor heat exchanger that extends into an entry air channel, a thermoelectric heat pump can remove heat from the fresh indoor air that a motorised fan draws from outside into the room. The indoor heat exchanger is said to be a heat sink block and appears to be a structure of aligned metal plates that form straight passages in line with the main air flow towards them. Their dominant frontal straight passage area and the smooth plate surfaces without transversal protrusions or recessions suggest that they surround air flow paths of highly laminar air flow with minimal air resistance. A similar outdoor heat exchanger on the other side of the thermoelectric heat pump is located indoors but extends into an exit air channel, through which air from the room is blown outdoors, thus disposing of the heat in air on its way to an outdoor environment, albeit with little heat per volume. Entry air channel and exit air channel extend through a special windowsill.

[0004] Likewise relevant is the cooled fan as described in US2017 / 0363307A1. The fan transports the waste heat from the hot plate via a thermally connected heat exchanger upwards within the same room, much of which will spread downwards eventually, worsening the effectiveness and the efficiency of the thermoelectric heat pump.

[0005] For application in buildings, with requirements such as avoiding condensation, thermoelectric cooling is known to be less efficient and less effective and more expensive than cooling with vapor-compression refrigeration. Proper heat removal is just as much a problem, requiring a large exit air channel or heat pipes or thermosiphons through walls or floors and usually all the way through the roof, a window frame or the building façade. This has prevented broad use despite some obvious advantages, such as decentral installation, retrofit installation, compactness and low maintenance.

[0006] The building air cooling system according to the invention also comprises at least one water duct that is thermally connected to the hot plate, for removing the heat that the thermoelectric heat pump has taken from the indoor heat exchanger, and that includes at least one water entry and at least one water exit. The water duct may be flat and placed against the hot plate, possibly with heat conducting paste in between, for instance a box with flow channels inside against a matrix of hot plates, or instead parallel tubes that are each placed against a row of hot plates. The water duct may even be complemented by the hot plates, the latter then constituting parts of a side wall of the former. Preferably, the water duct is thermally connected to the hot plate such that heat transfer is fully caused by temperature difference, that is, without mechanical assistance such as a pump that circulates a heat transport fluid from the hot plate to the water duct and back.

[0007] Moreover, the building air cooling system according to the invention comprises at least one flow-influence device that is configured to influence the flow through the water duct. The flow-influence device may be binary, such as an actuated shut off water valve or a positive displacement water pump with a fixed speed motor, but preferably it is more versatile, for instance a flow regulating water valve or for instance a variable speed driven axial flow water pump and a shut off water valve in series.

[0008] Such building air cooling systems are described as room air conditioners in US2013 / 0319014A1. The hot plates of the thermoelectric heat pumps therein are located at a water duct, which is also part of a closed-loop plumbing system of the building, namely a central heating system with several branched loops. The duct is said to carry for example a water-based liquid, which probably consists of rusty water and an inhibitor against freezing and oxidation. Heat from the hot plate is disposed of through the water exit of the water duct towards an outdoor environment, perhaps via switchable cooling ribs of the central heating system in a well-ventilated boiler room. It is unclear how the water flow through the water duct is set. A central heating system typically comprises a single water pump. The water pump services room air conditioners in different rooms apparently without balancing the heat removal in each. The central heating system apparently cannot at the same time provide heat for showers and hot water taps of a freshwater plumbing system, as it is customary.

[0009] The object of the invention is to improve indoor air cooling.

[0010] According to the invention, the building air cooling system further comprises at least one entry water conduit that is flow-capably connected to the water duct at the water entry thereof and that is configured flow-capably to connect to a plumbing system of a building, as well as at least one exit water conduit that is flow-capably connected to the water duct at the water exit thereof and that is configured at its far end to dispose of heat from the indoor heat exchanger towards an outdoor environment. By implication, the entry water conduit and the exit water conduit are not also part of the plumbing system. Once they are connected, the plumbing system can operate as before if the flow through them and the water duct in between is closed off. Either conduit may include a pipe, a tube, a hose or similar. The conduit may be integrally connected to a plumbing system by replacing a pipe with a T-pipe or integrally connected to the water duct already in production. The entry water conduit may have an open end for dipping into a plumbing system reservoir and taking water. The exit water conduit may have an open end for pouring heated water into a drain. Advantageously however, the entry water conduit or the exit water conduit is configured flow-capably to connect at either end by including a flow-capable connector there, more advantageously a typically suitable flow-capable connector, on its plumbing system end more advantageously a flow-capable connector to at least two pipe endings of the respective plumbing system. There, it may match a typical water pipe terminal, such as threaded or flanged or naked water pipe ending of a typical size, or a typical water pipe attachment, such as a typically shaped tap, spigot or faucet.

[0011] According to the invention, the flow-influence device is configured to act in the entry water conduit, the water duct or the exit water conduit, somewhere in between the flow-capable connection of the entry water conduit to the plumbing system and the far end of the exit water conduit. For instance, the flow-influence device may act at the flow connection of the entry water conduit to the plumbing system, or downstream in every branched-off entry water conduit or further downstream in the respective water duct or further downstream in the respective exit water conduit branch or further downstream in the exit water conduit past the point where the latter have joined. For instance, the flow-influence device may act as far downstream as where the exit water conduit opens above a drain.

[0012] Preferably, the entry water conduit of a building air cooling system according to the invention is configured flow-capably to connect to an open-loop plumbing system of a building. Usually, these are present in a building even if closed-loop systems are not. Connection to a closed-loop system necessitates the flow-capable connection of the exit water conduit as well, which necessitates cooling efforts to dispose of heat towards an outdoor environment if effectiveness and efficiency are to be preserved. Preferably, the entry water conduit and the exit water conduit are configured to connect to a plumbing system for providing potable water, respectively for disposing of wastewater. These plumbing systems are especially attractive, because they are typically available close to living quarters, where cooling is desired. However, the standardised diameter of freshwater plumbing pipes in the branches close to living quarters typically can be as low as half an inch. The water pump that feeds them is likely not sized to yield way beyond expected use. Moreover, in many parts of the world the supply of water is limited or expensive. A lack of local flow capacity or general availability can be alleviated by using a thermoelectric heat pump to multiply the uptake of heat per volume water. In this way, plumbing systems for providing potable water can support indoor air cooling besides simultaneously meeting the purpose for which they were designed.

[0013] Especially if a building air cooling system according to the invention is using local photovoltaic power, the water duct is thermally well connected to the hot plate by a phase-change material that is in a vessel and that is thermally connected to both. A phase-change material has a high volumetric latent heat storage capacity, which makes for an excellent primary heat transport fluid. After a sustained operation of the building air cooling system, in other words after the sun has set, the phase-change material will long continue to absorb heat, thus removing rest heat from the system, which otherwise would dissipate, also into indoor air. The phase-change material changes its phase at a favourable temperature of the hot plate for the operation of the thermoelectric heat pump. Heat transfer is caused by the high temperature at the hot plate, courtesy of the thermoelectric heat pump, being at or above the phase-change temperature, which in turn is higher than the temperature of the water that travels through the water duct. Similarly, the indoor heat exchanger is thermally well connected to the cold plate by a second, different phase-change material in another, second vessel that is thermally connected to both. Then, the indoor air may be cooled down after the thermoelectric heat pump has shut down. This increased lag is desirable in some applications, notably so when using local photovoltaic power only. If in operation a material phase-changes from solid to liquid and back, it preferably has a high thermal conductivity when solid.

[0014] The flow-influence device of a building air cooling system according to the invention preferably includes a flow regulating water valve. In some applications, the flow-influence device favourably includes a small water pump. Either way, the building air cooling system according to the invention advantageously comprises a flow sensor or a pressure sensor configured to act in the entry water conduit, the water duct or the exit water conduit, somewhere in between where the entry water conduit is configured flow-capably to connect to a plumbing system of a building and the far end of the exit water conduit. A flow sensor may be an ultrasound flow meter, an impeller wheel meter, an orifice plate flow meter for instance. A water temperature sensor adds information on the heat flow. Said sensors allow a flow controller to find a good balance between the water pumping effort and water consumption to achieve good thermoelectric effectiveness and efficiency at the required air-cooling performance. A water pressure sensor allows testing whether the system is functional and in particular free of leaks but can also substitute a flow sensor if the flow controller has stored information about the amount of flow at different pressure values, possibly so at different water temperatures before and after the water flows through the water duct. The flow controller is configured to generate output based at least on the flow sensor output respectively the pressure sensor output and based on at least one setpoint and is configured to set the performance of the flow-influence device in accordance with their output.

[0015] On a related note, at the other side of the thermoelectric heat pump, the indoor heat exchanger of a building air cooling system according to the invention advantageously includes a heat-conductive foam with air flow paths therethrough. Techniques in powder metallurgy and additive manufacturing allow accurate and cost-effective production of heat-conductive foams. Less accurate techniques, such as sintering pre-shaped pieces, may suffice in some applications. The heat-conductive foams may consist of a metal or an alloy, preferably an alloy with a high content of aluminium, or a conductive ceramic, for example aluminium nitride composites, or the like. They may be shaped as a network of interconnected strips, say, a tree network or a mesh network such as a porous metal foam, or rather as a folded sheet structure, in particular with a near minimal surface. They may be quasi-chaotic or periodical. They may be made sufficiently hollow for air to flow through. They may be made appropriately shaped to exchange heat with the air effectively. They may be made sufficiently solid for heat to be conducted therein.

[0016] Advantageously, in a properly installed building air cooling system according to the invention, at least some air flow paths through the heat-conductive foam do not include a straight passage in line with the main air flow towards the air flow path. Air must flow towards the heat-conductive foam predominantly in main directions before being diverted on a local scale by flowing around the leading edges of the heat-conductive foam material itself, lest the indoor heat exchanger is not configured to remove heat from the indoor air. If the building air cooling system comprises a motorised ventilator, the effect of an initial rotational component of the airspeed often can be neglected, or else sufficiently well estimated. The same holds true for the effect of standing sound waves inside an air channel. Alternatively, without a ventilator or slanted walls nearby, the main air flow direction towards the heat-conductive foam is almost vertically downwards, because the air density increases when the air is cooled therein. An occasional interference by other air flow in the room may lead to a temporary reduction of effect or of efficiency but can be ignored for the purpose of the invention.

[0017] Heat-conductive foams further differentiate from US2013 / 0319014A1, which indicates indoor heat exchangers that consist of fins on the cold plate. The fins are specified as pieces of sheet metal, ribs, fingers et cetera. They are shown in the figures to be freestanding within an air channel, therefore not constituting walls around paths for the air to flow through them. In particular, air flow paths at an angle to the main air flow towards the indoor heat exchanger in operation as intended are absent.

[0018] Preferably, the ratio of the average cross-sectional area of the heat-conductive foam to the average cross-sectional area in between its material decreases if the distance increases from where the heat-conductive foam is thermally connected to the cold plate. This can be achieved by giving the heat-conductive foam fewer material parts per unit volume or by giving it thinner material parts. It can also be achieved if the shape of the heat-conductive foam tapers away from where it is thermally connected to the cold plate of the thermoelectric heat pump. Then the envelope of such cross sections closes in on itself with increasing distance, which has a similar effect even if the content of the heat-conductive foam is homogenous. Its shape preferably tapers away essentially horizontally in operation as intended. If the cold plate of the thermoelectric heat pump in operation extends horizontally, the heat-conductive foam might resemble a discus that overhangs the thermoelectric heat pump.

[0019] Structures that include a heat-conductive foam for heating or cooling solid objects are known from WO2018 / 077321. The object for example is a vehicle battery, a fluid container or a microprocessor. Some structures comprise a thermoelectric heat pump that is thermally connected to the object at one of the two contact plates of the thermoelectric heat pump, which plate therefore is cold while cooling the object. On its opposite side, at the hot plate during cooling, the thermoelectric heat pump is thermally connected to a heat-conductive foam with air flow paths therethrough. The indoor heat exchanger disposes of waste heat or, so to speak, waste chill in the surrounding air, based on the needs of the object, not based on the needs of, say, building air cooling. If closed loop control would be added, a sensor would sense the object temperature and not a measurand for a building air cooling demand, such as room air temperature, outside temperature, daylighting, dew point, volatile organic components or occupancy. Some figures show a cooling pipe above a vertically tapered heat-conductive foam on top of a thermoelectric heat pump. The cooling pipe contains a liquid of unspecified nature. How the cooling pipe proceeds at either end is not disclosed, but a continuous circulation is suggested in the discussion of the art. There is no mention of a pump or a valve. Moreover, if one assumes this orientation of the structure and given that the structure only makes sense for cooling the thermally connected object, the cooling pipe slows down or even sends down rising hot air within the heat-conductive foam, making the air flow towards the heat-conductive foam chaotic, slow and instable. A heat exchanger that by design is not regularly exposed to a main air flow in operation as intended, is not configured to remove heat therefrom.

[0020] Preferably, in a simply connected region on the heat-conductive foam of a building air cooling system according to the invention, straight passages through the heat-conductive foam in line with the main air flow towards them in operation as intended are absent or contribute less than 44% to the frontal area of the region, preferably less than 36%, and the corresponding part of the indoor heat exchanger extends to where the indoor heat exchanger is thermally connected to the cold plate, and the frontal area of the region is at least half the frontal area of the heat-conductive foam. Disturbing the air flow on entry into and within the heat-conductive foam of a building air cooling system by reducing the frontal area of the straight passages therethrough disproportionately improves the exchange of heat therewith, generally improving the conductivity of heat within the heat-conductive foam too, while the air flow through the heat-conductive foam can be kept at acceptable levels. The heat-conductive foam structure can be chosen better to fulfil requirements for application in buildings, in particular effectiveness without condensation and efficiency, while keeping practical upper limits on production costs and size, because the heat removal at the far side of the thermoelectric heat pump by the water flow through the water duct can keep the cold plate at a stable temperature within a narrow range. This temperature can be estimated by using signals from other sensors, in particular a heated water temperature sensor and a water flow sensor, combined with information on the cooling performance of the thermoelectric heat pump. It is best measured by an integrated temperature sensor in or nearby the thermoelectric heat pump.

[0021] Instead of the whole heat-conductive foam having low straight passage area, a simply connected region thereon suffices, if large enough and if the corresponding part of the indoor heat exchanger, that is the passage-poor part behind the region in the main direction of the incoming air flow, stretches out to where it is thermally connected to the cold plate of the thermoelectric heat pump. One could put heat-conductive foam parts with wider or more densely placed straight passages in line with the incoming air flow next to the region, provided that they do not hinder the heat being conducted within the heat-conductive foam to where it is thermally connected to the cold plate, for example at an edge of the heat-conductive foam. These extra heat-conductive foam parts may raise the average frontal area contribution by straight air flow passages substantially, the major restriction being the size of the building air cooling system, while the heat-conductive foam in the aforesaid region still brings benefits of the invention.

[0022] The main air flow towards the structures of WO2018 / 077321 for heating or cooling solid objects with a thermoelectric heat pump and a heat-conductive foam with air flow paths therethrough is difficult to predict in isolation. Initial figures show a thermoelectric heat pump and a porous heat-conductive foam with straight passages in various directions therethrough on top. The straight passages cover more than half of the respective frontal area. It is uncertain from where one would expect air to flow towards the indoor heat exchanger in operation as intended, which depends on the shape and temperature of the solid object and other objects nearby, on the orientation of the structure and on the presence of a fan. Some structures as depicted in WO2018 / 077321 are irregularly printed heat-conductive foams that do without a thermoelectric heat pump. The chaotic air flow paths therethrough appear to include large straight passages, but a frontal area estimation is impossible for lack of detail and a distinguishable background. Anyhow, the main air flow, if any, may not be aligned with the angle of view.

[0023] Advantageously, the building air cooling system according to the invention also comprises at least one cooling demand sensor that is configured to sense a measurand for the cooling demand, as well as a cooling controller that is configured to generate output based on the cooling demand sensor output and based on at least one setpoint, and that is configured to set the performance of the thermoelectric heat pump in accordance with its output.

[0024] Examples of a measurand are a change of passive infrared radiation by human movement in the room, the lighting level in a windowless room or something else that indicates occupancy. Preferably, a measurand indicates air temperature, for instance by means of a temperature sensitive resistor, an electromagnetic radiation sensitive semiconductor junction or an acoustic wave sensitive piezoelectric substrate. Heating or cooling is often triggered by a sensor of the air temperature outside the building. More preferably however, alternatively or at best additionally, a measurand indicates the temperature of air inside the room. Ideally, the building air cooling system also comprises a sensor of indoor air humidity, say, a dew point sensor. Air humidity by itself is not a measurand for a cooling or heating demand, but it is if combined with the room air temperature.

[0025] The cooling demand sensor and the cooling controller might be integrated into a component of the building air cooling system, but a part of either might be remote. If so, that cooling demand sensor or cooling controller includes a module in the component of the building air cooling system that is configured to receive data and to act in accordance therewith. For example, a cooling control software runs on a dedicated server or on a cloud server. Then, the cooling controller includes a module in the component of the building air cooling system that is configured to receive control data and accordingly to set the performance of the thermoelectric heat pump. Also, the cooling controller might perform a short-term control locally and a remote analysis for optimising the short-term control, especially to deduct whether relevant circumstances of operation have changed or to adapt control if it knows that they have. Preferably, the cooling controller is configured to determine a need or to receive a request for user feedback and is configured to enquire feedback from a user. It preferably is configured to register an electronic device of the user and is configured to enquire feedback by means of the device, for instance by presenting a questionnaire or by using a large language model.

[0026] The cooling controller sets the performance of the thermoelectric heat pump for instance by determining its electrical power intake. It might closed-loop-regulate the thermoelectric heat pump in any way, for instance in the two-point way by switching the thermoelectric heat pump on and off, or for instance in continuous or near-continuous modulation in response to the proportional, the integral or the derivative of the difference between a processed sensor output and the setpoint. Advantageously however, the cooling controller is configured at times to amend its output as compared to mere regulation for restricting the temperature difference between the cold plate and the hot plate of the thermoelectric heat pump, in particular with the intention to restrict the difference to a maximum that is below 35°C, for staying in the most efficient performance range of the thermoelectric heat pump.

[0027] Likewise, the cooling controller advantageously is configured at times to amend its output as compared to mere regulation for restricting condensation at the cold plate of the thermoelectric heat pump or condensation on the heat-conductive foam. Advantageously, it is configured to calculate the performance of the thermoelectric heat pump at which condensation occurs. This calculation might require an extra humidity sensor or dew point sensor, the frequent reception of weather data or an initial thermodynamic modelling specific to the room. In this way, the heat-conductive foam can approach the dew point temperature closely without unacceptably crossing it. Advantageously, the cooling controller in particular is configured at times not to make the thermoelectric heat pump cool the cold plate even though the sensor output and the setpoint would require doing so.

[0028] Typically, indoor heat exchangers within a room are placed close to the ceiling or above a false ceiling. In a building air cooling system according to the invention, the thermoelectric heat pumps may be arranged at a distance, for instance close to where a freshwater pipe and a three-phase electricity plug happen to be. In that case, primary fluid conduits must circulate a primary heat transport fluid, such as water, between the indoor heat exchangers and the cold plates, likely with the help of a primary fluid pump. Preferably, the thermoelectric heat pump and the water duct are fixedly connected with respect to each other within a heat removal unit, or the indoor heat exchanger is fixedly connected with respect to the thermoelectric heat pump within a room air cooling unit. Production is more efficient if all three are fixedly connected with respect to each other within a room air cooling unit.

[0029] The invention further concerns a room air cooling unit that comprises at least one thermoelectric heat pump that includes a first plate and a second plate, between which in operation it transfers heat. It also comprises at least one indoor heat exchanger that is thermally connected to the first plate and that includes a heat-conductive foam with air flow paths therethrough. Furthermore, it comprises at least one water duct that is thermally connected to the second plate and that includes at least one water entry and at least one water exit. The thermoelectric heat pump, the indoor heat exchanger and the water duct are fixedly connected with respect to each other within the room air cooling unit. Preferably, from every perspective, straight passages through the heat-conductive foam in a simply connected region thereon are absent or contribute less than 44% to the frontal area of the region, more preferably less than 36%, and the frontal area of the region is at least half the frontal area of the heat-conductive foam. For keeping the cold plate of the thermoelectric heat pump at a stable temperature within a narrow range, the room air cooling unit according to the invention advantageously comprises at least one temperature sensor that is fixedly connected within the room air cooling unit too. This may be a temperature sensor near or in the thermoelectric heat pump, for instance sensing the temperature of the heated water or the temperature of the cold plate itself.

[0030] The invention further concerns a method for installing a building air cooling system. The method comprises at least the following steps. At least one thermoelectric heat pump is provided that includes a cold plate from which it transfers heat in operation as intended heat is transported and that includes a hot plate to which it transfers heat in operation as intended heat is transported. At least one indoor heat exchanger is provided and thermally connected to the cold plate. At least one water duct that includes at least one water entry and at least one water exit, is provided and thermally connected to the hot plate. At least one entry water conduit is provided and flow-capably connected to the water duct at the water entry thereof. At least one exit water conduit is provided and flow-capably connected to the water duct at the water exit thereof. At least one flow-influence device is provided and assembled so that in operation as intended it influences the flow through the water duct by acting in the entry water conduit, the water duct or the exit water conduit.

[0031] The method further comprises at least the following steps, when opportune. The provided items are installed in a building such that the indoor heat exchanger in operation as intended removes heat from the indoor air and such that the entry water conduit is flow-capably connected to the plumbing system and such that the exit water conduit in operation as intended at its far end disposes of heat from the indoor heat exchanger towards an outdoor environment.

[0032] The invention is illustrated in the drawings as follows. Figure 1 shows a sketch of a room that contains a first building air cooling system according to the invention. Figure 2 shows a sketch of a part of the same room with some detail of how the first building air cooling system is flow-capably connected to a washbasin. Figure 3 shows a sketch of a room and a nearby toilet room that contain a second building air cooling system according to the invention. Figure 4 shows a sketch of a room and a part of an adjacent boiler room that contain a third building air cooling system according to the invention, with some detail of the flow control components thereof. Figure 5 shows a cross-sectional sketch of a room air cooling unit according to the invention, comprising an indoor heat exchanger, a thermoelectric heat pump and a water duct. Figure 6 shows a sketch of a rectangular cut-out of a heat-conductive foam of an indoor heat exchanger of a building air cooling system or a room air cooling unit according to the invention. Figure 7 shows a sketch of a rectangular cut-out of a preferred heat-conductive foam far from where the indoor heat exchanger is thermally connected to the cold plates of the thermoelectric heat pumps. Figure 8 shows a sketch of a rectangular cut-out of the preferred heat-conductive foam close to where the indoor heat exchanger is thermally connected to the cold plates of the thermoelectric heat pumps.

[0033] Shown schematically in figure 1, a first building air cooling system according to the invention comprises room air cooling units near the ceiling of room 1, each with an indoor heat exchanger 3 for removing heat from the indoor air and with a vessel 70 on top. Thermoelectric heat pumps are present where indoor heat exchanger 3 and vessel 70 meet, but not depicted.

[0034] Connected to the open-loop freshwater plumbing system 40 of the building is an entry water conduit 50 that branches off towards every room air cooling unit, where it is flow-capably connected at water entries 30 to unseen water ducts inside the vessels 70. Likewise, for disposing of the heat outside the building, a branched exit water conduit 51 is flow-capably connected at water exits 31 of the same water ducts and is connected at its far end to the open-loop wastewater plumbing system 41. The exit water conduit 51 and indoor-air exposed parts of the wastewater plumbing system 41 are enclosed by heat isolation material.

[0035] In the entry water conduit 50, a water pump 34 and parallel flow regulating water valves 35, 36, 37, 38 act in sequence as flow-influence devices.

[0036] The indoor air is monitored by an air temperature sensor 61 and an air humidity sensor 63. Their sensor output is processed by an unshown air cooling controller, which sets the performance of the thermoelectric heat pumps. An unshown flow controller sets the performance of the water pump 34 accordingly, using sensor output from a flow sensor 60 in the entry water conduit 50. The controllers may be in the room or elsewhere on site or remote. The flow controller checks whether the water pressure is within an acceptable range by virtue of a pressure sensor 62 in the entry water conduit 50.

[0037] Figure 2 shows in more detail how the entry water conduit 50 includes a connector 52 that is flow-capably connected to the freshwater plumbing system near a washbasin. Pipe ending 42 of the plumbing system is hidden behind a cover plate and pipe ending 43 is invisibly located within a fastening nut. The connector 52 is a shut off water valve by virtue of manually operated flow-influence devices 35. The exit water conduit 51 includes a connector 53 for a flow-capable connection to the wastewater plumbing system 41 at pipe endings 44, 45 thereof, each of which being located inside a fastening ring. By having connector 52 and connector 53, the entry water conduit 50 and the exit water conduit 51 obviously are configured flow-capably to connect to a plumbing system 40 for potable water, respectively a wastewater plumbing system 41.

[0038] A second building air cooling system according to the invention as depicted schematically in figure 3 is functionally equivalent to the first one, with a few exceptions. Instead of a flow regulating water valve for each room air cooling unit in series with a water pump, entry water conduit 50 has a single water valve 35 in parallel with a water pump 34. Moreover, the depicted parts of the building air cooling system are divided between a room, a hallway and a toilet room.

[0039] Figure 4 schematically shows a room and a part of an adjacent boiler room that contain a third building air cooling system according to the invention. Although functionally equivalent again, an exit water conduit 51 is now connected to the same open-loop plumbing system 40 as an entry water conduit 50 is further upstream. Also, an exit water conduit 51 includes a passage through a heat exchanger 80 for preheating water that is fed into an unshown boiler system 81. Also, the water flow through the entry water conduit 50 is not measured directly but calculated as a stored curve against the signal value of a pressure sensor 62 with adjustments as stored curves against the signal values of temperature sensors 64, 65 in the exit water conduit 51 and the entry water conduit 50, respectively.

[0040] Detail of the flow control components is presented only in figure 4 but the flow control components should be considered comprised by way of example in the building air cooling systems according to the invention as depicted in other figures, mutatis mutandis.

[0041] A wireless communication module 14 can receive indoor air temperature data from a separate air temperature sensor 61, which is mounted in the room at a distance from the room air cooling units and from the indoor air circulation through their heat-conductive foams. The communication module 14 relays the sensed data to a subordinate cooling controller part 90. Setting the performance of the thermoelectric heat pumps, the subordinate cooling controller part 90 performs closed loop regulation on the basis of room temperature data from the air temperature sensor 61 and on the basis of room humidity data from the air humidity sensor 63. This combination of measurands is used for more precisely determining a cooling demand if a demand as such is present, for instance according to a schedule or as established by an occupancy sensor. However, the subordinate cooling controller part 90 amends its output if needed to restrict the temperature difference between the cold plates and the hot plates to 30°C. Also, it amends its output if needed to restrict condensation on the cold plates or on the heat-conductive foam 3. In both cases, it makes the thermoelectric heat pumps cool their cold plates less than the sensor output would require when going for the one or more setpoints. The setpoint for the closed loop regulation is determined by a superior cooling controller part 91, taking occupant preferences into account, if available. The superior cooling controller part 91 is a cloud server on which a dedicated software runs, which communicates with the subordinate cooling controller part 90 through communication module 14. The superior cooling controller part 91 adjusts the algorithm by which the subordinate cooling controller part 90 calculates the cooling performance of the thermoelectric heat pumps at which in the circumstances condensation would occur. It also analyses the power consumption over time and offers an occupant various control models via an app on his smartphone. If the superior cooling controller part 91 determines a need or receives a request for user feedback, it enquires feedback by means of questionnaires that are presented by the app.

[0042] A flow controller 92 of the building air cooling system in figure 4 uses the output from the pressure sensor 62 and temperature sensors 64, 65 to set the performance of the water pump 34 and the valve 35. It aims to remove enough heat through water duct 8 to keep a hot plate temperature for the thermoelectric heat pumps to hold the temperature at the cold plate steady within a desired range yet keep the water pumping effort and water consumption low. A difference in the readings from water temperature sensors 64, 65 helps establish actual information on the heat removal.

[0043] Figure 5 schematically shows in cross-section a room air cooling unit according to the invention that fits well in the building air cooling system according to the invention as depicted in previous figures. The room air cooling unit consists of thermoelectric heat pumps 10, arranged in a matrix, each including firstly a cold plate 11, from which it transfers heat in operation as intended, and secondly a hot plate 12, to which it transfers heat in operation as intended. The thermoelectric heat pumps 10 are Peltier elements "CP30338" from the company CUI Devices.

[0044] An indoor heat exchanger 3 is a heat-conductive foam 3 with air flow paths therethrough that is thermally connected to the cold plates 11. It is configured to remove heat from the indoor air if the room air cooling unit is installed horizontally without nearby objects, as per instruction manual, so that the indoor air can freely approach from above along near-vertical lines. In a simply connected region thereon that covers the entire indoor-air-exposed topside, vertical straight passages through the heat-conductive foam 3 contribute to the frontal area between 36% at the rim and 9% at the inside. From any other perspective, the area contribution by straight passages through the indoor heat exchanger 3 is less than 36%. The corresponding part of the indoor heat exchanger 3 to said region is the straight-passage-poor part below, which extends sideways to where the indoor heat exchanger 3 is thermally connected to the cold plates 11.

[0045] A vessel 70 on top encloses a phase-change material 71 and two parallel branches of a water duct 8, which includes a unshown joint water entry and an unshown joint water exit. The thermoelectric heat pumps 10, the heat-conductive foam 3 and the water duct 8 are fixedly connected to the vessel 70. By virtue of the phase-change material 71, which acts a as primary heat transfer fluid, the water duct 8 is thermally connected to the hot plate 12. Finally, heat isolation material 72 against some walls of the vessel 70 hinders the heated phase-change material 71 from transferring heat back into the indoor air.

[0046] Not depicted are two temperature sensors that are fixedly connected within the room air cooling unit. One temperature sensor is integrated into the matrix of thermoelectric heat pumps 10 in the plane where it touches the heat-conductive foam 3, effectively sensing the temperature of a nearby cold plate. The second temperature sensor is fixedly connected near the water exit of the water duct 8 and senses the temperature of the heated water that leaves the room air cooling unit.

[0047] Figure 6 presents structural detail of the content of a heat-conductive foam 3 of a room air cooling unit or a building air cooling system according to the invention. The structure closely resembles a gyroid, the surface of which is curved everywhere. The wall thickness is 140 micrometres. Holes of around 1mm are recognisably lined up to make four straight passages 18 for the air through the heat-conductive foam 3. Their direction is in line with the main flow of indoor air from the room towards them. Such straight passages contribute 19% to the frontal area of the heat-conductive foam 3. Flow paths with a straight passage in different directions are interconnected, requiring the approaching air to turn a corner first.

[0048] Along the air flow paths of the four straight passages 18, the path wall 19 protrudes and recedes transversally 5 times each within the depicted rectangular volume. Every time, the local reduction of the air flow path cross sectional area is an estimated 80% of the previous air flow path cross sectional area, which covers the large, twisted funnel that leads up to the hole of straight passage 18. Downstream, the estimation of the local increase is around 500%, for the same reason. The largest transversal protrusion is around 0.7mm, all the way from where the funnel meets up with the funnel of the next parallel straight passage 18 or with the funnel of some side channel 20 that branches off under a different angle. Such interconnected side channels protrude and recede transversally less frequently within the length of the depicted rectangular volume.

[0049] In figure 7, a preferred heat-conductive foam of an indoor heat exchanger of a room air cooling unit or a building air cooling system according to the invention especially suits a flattish indoor heat exchanger as depicted in figure 5 and is explained here as being part thereof. The structure again resembles a gyroid, but it is not uniform. The depicted rectangular volume is close to the edge of the heat-conductive foam 3 and thus far from where it is thermally connected to the cold plates 11 of the thermoelectric heat pumps 10. The walls are 50 micrometres thick and fragile. Four vertical straight passages 21 on the top and at the bottom of the depicted rectangular volume are quite large and contribute 36% to the frontal area of the heat-conductive foam, near the upper limit, because in practice the heat conduction within the walls of the heat-conductive foam can just about keep up to avoid overly steep temperature gradient drops in thermodynamic equilibrium. Also, the heat exchange between air and path wall starts to be affected by the reduced disturbance of the air flow.

[0050] Figure 8 shows the same preferred heat-conductive foam, but much closer to where the indoor heat exchanger is thermally connected to the cold plates 11 of the thermoelectric heat pumps 10, underneath the thermoelectric heat pumps 10 themselves. The wall thickness at 180 micrometres improves the local heat conduction within the heat-conductive foam material, allowing the overall flat shape of the heat-conductive foam 3, yet keeping the size of the inner temperature gradient small everywhere in dynamic equilibrium with a uniform temperature of the incoming air.

[0051] As can be seen by comparing figure 7 and figure 8, the ratio of the average cross-sectional area of the heat-conductive foam 3 to the average cross-sectional area in between its material decreases with the increased distance from where the heat-conductive foam 3 is thermally connected to the cold plates 11. This was done by giving the heat-conductive foam 3 in figure 7 thinner material parts. Heat from there together with heat that is collected on the way to the cold plates 11 can flow equally fast thanks to the greater wall thickness of figure 8. Therefore, the inner temperature gradient is uniform despite the straight shape of the heat-conductive foam, like a brick or like a disk, and the gradient is uniformly small, meaning that the heat-conductive foam 3 can be large, cooling down a large throughflow of indoor air to a reliably uniform temperature.

Claims

1. Building air cooling system, comprising at least one thermoelectric heat pump (10) that includes a cold plate (11) from which it transfers heat in operation as intended and that includes a hot plate (12) to which it transfers heat in operation as intended, at least one indoor heat exchanger (3) that is thermally connected to the cold plate (11) and that is configured in operation as intended to remove heat from the indoor air, at least one water duct (8) that is thermally connected to the hot plate (12) and that includes at least one water entry (30) and at least one water exit (31), and at least one flow-influence device (34, 35, 36, 37, 38) that is configured to influence the flow through the water duct (8), characterised in that the building air cooling system comprises at least one entry water conduit (50) that is flow-capably connected to the water duct (8) at the water entry (30) thereof and that is configured flow-capably to connect to a plumbing system (40, 41) of a building, at least one exit water conduit (51) that is flow-capably connected to the water duct (8) at the water exit (31) thereof and that is configured at its far end to dispose of heat from the indoor heat exchanger (3) towards an outdoor environment, and the flow-influence device (34, 35, 36, 37, 38) is configured to act in the entry water conduit (50), the water duct (8) or the exit water conduit (51).

2. Building air cooling system according to the preceding claim, wherein the entry water conduit (50) is configured flow-capably to connect to an open-loop plumbing system (40, 41) of a building.

3. Building air cooling system according to either of the preceding claims, wherein the entry water conduit (50) is configured flow-capably to connect to a plumbing system (40) of a building for providing potable water.

4. Building air cooling system according to either of the preceding claims, wherein the exit water conduit (51) is configured at its far end flow-capably to connect to a plumbing system (40, 41) of a building5. Building air cooling system according to either of the preceding claims, wherein the entry water conduit (50) or the exit water conduit (51) is configured flow-capably to connect by including a flow-capable connector (52, 53).

6. Building air cooling system according to either of the preceding claims, wherein the flow-influence device (34, 35, 36, 37, 38) includes a flow regulating water valve (35, 36, 37, 38).

7. Building air cooling system according to either of the preceding claims, wherein the flow-influence device (34, 35, 36, 37, 38) includes a water pump (34).

8. Building air cooling system according to either of the preceding claims, wherein the building air cooling system comprises a flow sensor (60) or a pressure sensor (62) that is configured to act in the entry water conduit (50), the water duct (8) or the exit water conduit (51), the building air cooling system comprises a flow controller (92) that is configured to generate output based at least on the flow sensor output, respectively the pressure sensor output, and based on at least one setpoint and that is configured to set the performance of the flow-influence device (34, 35, 36, 37, 38) in accordance with its output.

9. Building air cooling system according to either of the preceding claims, wherein the indoor heat exchanger (3) includes a heat-conductive foam (3) with air flow paths (20) therethrough.

10. Building air cooling system according to the preceding claim, wherein at least some air flow paths (20) through the heat-conductive foam (3) do not include a straight passage (18, 21) through the heat-conductive foam (3) in line with the main air flow towards the air flow path (20) in operation as intended.

11. Building air cooling system according to either of the preceding claims as of claim 9, wherein in a simply connected region on the heat-conductive foam (3), straight passages (18, 21) through the heat-conductive foam (3) in line with the main air flow towards them in operation as intended are absent or contribute less than 44% to the frontal area of the region, the corresponding part of the indoor heat exchanger (3) extends to where the heat-conductive foam (3) is thermally connected to the cold plate (11), and the frontal area of the region is at least half the frontal area of the heat-conductive foam (3).

12. Building air cooling system according to either of the preceding claims, wherein the water duct (8) is thermally connected to the hot plate (12) by a phase-change material (71) that is in a vessel (70) and that is thermally connected to both.

13. Building air cooling system according to either of the preceding claims, wherein the indoor heat exchanger (3) is thermally connected to the cold plate (11) by a second phase-change material that is in a second vessel and that is thermally connected to both.

14. Room air cooling unit, comprising at least one thermoelectric heat pump (10) that includes a first plate (11) and a second plate (12) between which in operation it transfers heat, at least one indoor heat exchanger (3) that is thermally connected to the first plate (11) and that includes a heat-conductive foam (3) with air flow paths (20) therethrough, and at least one water duct (8) that is thermally connected to the second plate (12) and that includes at least one water entry (30) and at least one water exit (31), wherein the thermoelectric heat pump (10), the indoor heat exchanger (3) and the water duct (8) are fixedly connected with respect to each other within the room air cooling unit.

15. Room air cooling unit according to the preceding claim, wherein from every perspective, straight passages (18, 21) through the heat-conductive foam (3) in a simply connected region thereon are absent or contribute less than 44% to the frontal area of the region, and the frontal area of the region is at least half the frontal area of the heat-conductive foam (3).

16. Room air cooling unit according to either of the preceding claims as of claim 14, wherein the room air cooling unit comprises at least one temperature sensor that is fixedly connected too within the room air cooling unit.

17. Method for installing a building air cooling system, comprising at least the steps of providing at least one thermoelectric heat pump (10) that includes a cold plate (11) from which it transfers heat in operation as intended and that includes a hot plate (12) to which it transfers heat in operation as intended, providing at least one indoor heat exchanger (3) and thermally connecting it to the cold plate (11) and providing at least one water duct (8) that includes at least one water entry (30) and at least one water exit (31) and thermally connecting it to the hot plate (12), providing at least one entry water conduit (50) and flow-capably connecting it to the water duct (8) at the water entry (30) thereof, providing at least one exit water conduit (51) and flow-capably connecting it to the water duct (8) at the water exit (31) thereof, and providing at least one flow-influence device (34, 35, 36, 37, 38) and assemble it so that in operation as intended it influences the flow through the water duct (8) by acting in the entry water conduit (50), the water duct (8) or the exit water conduit (51), and when opportune, installing provided items in a building such that the indoor heat exchanger (3) in operation as intended removes heat from the indoor air and such that the entry water conduit (50) is flow-capably connected to the plumbing system (40, 41) and such that the exit water conduit (51) in operation as intended at its far end disposes of heat from the indoor heat exchanger (3) towards an outdoor environment.

Images