WO2008131507A2

WO2008131507A2 - Air conditioning apparatus made of heat pipes

Info

Publication number: WO2008131507A2
Application number: PCT/BR2008/000126
Authority: WO
Inventors: Irineo Constantino Schuch Ortiz
Original assignee: Schuch Ortiz Irineo Constantin
Priority date: 2007-04-27
Filing date: 2008-04-28
Publication date: 2008-11-06
Also published as: WO2008131507A3; BRPI0702195A2; BRPI0702195C1

Abstract

The apparatus has an upper serpentine i.e. condenser, with pipes and turns in a horizontal plane, and a lower serpentine (E) i.e. evaporator, with pipes and turns in a vertical plane. Connecting pipes (TA, TB) constitute an adiabatic part of the apparatus, and connect the upper serpentine with the lower serpentine. A working fluid i.e. refrigerant, is maintained with an evaporation/condensation point below a temperature of environment air to be cooled and higher than a temperature of water deposit (A) where heat is to be sent.

Description

IR CONDITIONING APPARATUS MADE OF HEAT PIPES

The present invention refers to i an air conditioning apparatus, based on heat transfer to a water deposit, made of a loop heat pipes that belongs to the technical section of the refrigeration industry. It comprises a lower part that is the evaporator part, with ia serpentine (coil) shape, with its pipes and turns in a vertical or almost vertical plane, bound by ascending pipfes to the upper part, the condenser part that is another serpentine that has its pipes and curves in a horizontal plane. The apparatus is a heat transfer device that uses latent!¹ heat of evaporation and of condensation to have the heat' transferred between from one site immersed in the environment air of the room

1 to be cooled and a second one, immersed in a water deposit i that works as a heat sink. '

The simplest thermosyphons and heat pipes comprise an evaporator part, where the working (refrigerant) fluid receives (extracts) heat from an environment or device as the fluid evaporates (fig 1). As consequence, the environment or device is cooled. The refrigerant fluid, in i its steam phase, goes to the condenser part, where as it condensates, it transfer the heat to the other environment or device that works as a heat sink. The condensed fluid, in the liquid phase, comes back to the evaporator zone where it evaporates again, with this cycle being continuously repeated.

In the loop thermosyphons and Heat pipes the steam goes from the evaporator to the condenser zone through a pipe and goes back through another (fig. 2) . In the thermosyphons the movement of the working fluid happens by gravity, with the steam phase going up, by difference of density, from the lower part that receives heat from, the I, environment or device to the upper part that is colder and that works as a heat sink. The fluid condensates in the i upper part and goes down by gravity as liquid phase to the lower part . In the heat pipes that are known according to the state of technology, the part that receives heat is not situated above the part that drain's heat, and it is necessary a system that uses capillary pressures to make the liquid phase go from the lower pa;rt to the upper part of the pipe. j

1

A serpentine heat pipe with the pipes and turns in the vertical plane may be considered a sequence of connected heat pipes in a series, where the end of one is connected with the beginning of the other (fig 3) . In such pipes series, the lower part with the U turns holds the liquid phase and the upper part, with inverted U-shape, the j steam phase. As it is filled up with the working

(refrigerant) fluid, and as it reaches the boiling temperature, the change to the steamj, phase first happens where the pressure is the lowest in P the vertical liquid column, that is, in the upper part that has the inverted U- i. shaped upper turns of the serpentine, where it is produced a space with steam, bound below in each portion by the remaining liquid. Therefore, the liquid phase remains in the lower part, in the U turn and in p !art of the ascending part. The same effect makes the levels' of the liquid phase i remain at the same level in all pipes¹. Above these liquid levels the steam pressure remains approximately equal in the container, comprised by the ascending pipes and the serpentine with the pipes and turns in^'; the horizontal plane i' of the condenser part. (Minimal differences in pressure are correlated with the height of the pipes, that work as thermosyphons. This state is reached 'after the filling of the apparatus with the working fluid, when the temperatures and pressures become equal in all parts of the apparatus.

An alternative for the described devices includes parallel series of pulsating (oscillating) heat pipes, working with the same goal, with the evaporator parts immersed in the environment air and the condenser part sunk in water. i

There has been a constant¹ evolution of the technology on thermosyphons, since itsj creation by Perkings in the midl800^rs and on the heat pipes, since its creation by Gaugler, in 1944. Informations on the subject may be obtained in Peterson, P: An Introduction to Heat Pipes, published by Wiley Interscience, New .York, 1994 and Dunn, PD & Reay, DA: Heat Pipes, 4ht edition, Pergamon Press, 1994. J

Precedents of the utilization , of serpentine heat pipes are described for another way of utilization and with a different configuration in the United States Patent number 5,921,315, dated 13/07/1999, and 5,845,702, dated 08/12/1998, from Khanh Dinh, Alachiia, Florida, U. S.A", which from the present invention ' represents another elaboration and with a new utilization.'

The air conditioning apparatus created up to the present times are frigorific engines, where the heat goes from one environment to another and that needs energy for working, that is, there is necessity of work provision under the form of compression of the refrigerant (working) fluid. The energy used for this work is the electrical one, delivered to the houses and companies and its cos^~s is considerable. For instance, a modern J apparatus, build up already with the concern of saving energy, o the split air type, of 30.000 BTU, only for refrigeration, without heating, consumes 2,9 kw/h. As the kw| cost of R$ 1,36 and imagining that it stays turned on| 10 hours/day, 100 days/year, working 1000 hours/year, consuming 2,900 kw/year, it will cost in 3 years, R$ 3.944,00 in energy consumption. Curiously, the buying costs of the apparatus is R$ 3,940,00, that is, every 3 years its buying cost is spent in electric energy consumption. '(To convert to U.S.A. dollars, consider the exchange rate R$fl,70 equivalent to 1 dollar) . I

In the heat transfer from the environment air to a i water deposit is crucial the difference between the heat

1 volumetric capacity (or thermal capacity) of the air and of

I the water. Their values are given by the products of specific heat x density; as an example, at 27 ° C (300° Kelvin), the thermal capacity of the air is 0,238 kcal/m3. 0C x 1,1614 kg/m3 = 0,276 m3. ⁰C and i the thermal capacity of the water is 0,990 kcal x 1.000 kg|m3. 0° C; therefore, the ratio of the volumes needed to | hold the same heat quantity is 0,276/990 = 0,00027, or, | in the reverse way, 3.58695. This means that, for the heat transfer of the amount of heat equivalent to a degree of temperature from the air of a room of 30 m3, for the needed amount of water is 8,3 1, if it remains still and that is not continuous renewed and if this calculation is not wrong. And for a 2O⁰C gradient of temperature, from 40 ⁰C from the air to 2O⁰C of the water, for example, it is necessary 166 1 of water, that is far below the standard capacity of water deposits of houses and buildings. Besides, one counts on the renewal of the water on the watier deposit, that is given by the average water consumption of a family, around 166 I/day. ^' I The goal of the invention is ^: to provide an air i refrigeration system through the hea't transfer from the environment air to a heat sink (drain) > composed of a water deposit, situated at a level above or ! at the same level of the room to be cooled. Such a refrigeration system differs from the ones already known by its construction array and its working, described in the sequence. The functioning of the air conditioning apparatus happensl naturally due to its i construction array and the working (refrigerant) fluid, not needing a compressor or any electro-mebhanic device for the heat exchange. I

The apparatus consists in aj; heat pipe with a serpentine format, composed of two parts, named the upper and lower part, bound by ascending pipes that are continuous with the ends of the serpentine. The upper part is composed of a finned serpentine which pipes and turns are in a horizontal plane, being thef condenser part. The lower part is composed of finned serpentine which pipes and turns are in a vertical or almost vertical plane, being the evaporator part. j

The preferred embodiment of the said apparatus is made of finned serpentines, made of; copper pipes or a similar material, compatible with the working fluid, and with fins of aluminum or a similar material, with proper spaces between them. The serpentines that comprise the air j^' conditioning apparatus work as heatj; pipes comprising a lower evaporator part, where the i^;working fluid gets (receives) heat from the environment and evaporates. Consequently, the environment air is !' cooled. The working fluid (refrigerant) in the steam phase, goes up by the ascending pipe due to the density difference till the upper part, that works as a heat sink. The heat is then transferred to this environment (water) or sink and the fluid is condensed again. The condensied fluid comes back, in liquid phase, due to its higher density, by the inner walls of the pipe to the lower evaporator part, with this cycle being repeated continuously. i

The heat transfer occurs by thej vaporization of the

[ working fluid in the lower part that goes up by the ascending pipes that is linked to the ends of the upper serpentine. In the upper part that j.is sunk in a water deposit, and due to the reduction of the steam temperature, the steam goes to a saturated state, : condensates and goes

I down to the serpentine heat pipe |iin the lower part, immersed in the environment to be cooled.

Against the finned serpentine, inj the lower evaporator part, one may set a system of forced air by a fan, in case it is needed a faster cooling of the air than the one obtained by simple convection. !'

The functioning of the air conditioning apparatus

part of higher temperature and so on, repeatedly. The system should be ready to hold the pressures that unfold with the temperature raise. τ|he refrigerant fluid should be chosen for being compatible',! with the containing pipes, range of working temperatures 'and pressures of the saturation steam that should not overload the pipes. Butane, iso-butane, 1, 3-butadiene, dimethyl-acethylene, ethylamine, ethyl benzene, methyl ether, metal bromide, mercaptan, neo-pentane, 2,2 dimethyl propane, and propane are options, but empiric tests, based on boiling temperatures and pressures of saturated steam at different external temperatures, expected in the: average environment, should guide the choice. Besides the heat transfer, that may happens with small differences in temperature between the environment air and i the water deposit, one counts also with the evaporation in the lower evaporator part. This leads the serpentine in contact with the environment air to be cooled well below the air temperature, in a| transient way. However, quite soon this air that was^', .in contact with the evaporator tends to get mixed with the rest of the remaining environment air and get ! warmer. This area, reaching the dew point, will lead to the condensation of the water that is the air. A local! porous surface that

I makes the adsortion of this humidity ;^' and traps the water into its pores, is bound to a pipe that works as a drain for this water, otherwise it would go back to the same environment by evaporation. Thus, ;even with a small

I¹ decrease of the temperature of the environment, there is a decrease of the relative humidity!' of the air that i contributes for the thermal comfort that is intended from an air conditioning apparatus . i¹

If the heat in the water deposit does not maintain satisfactorily low temperatures, this ι. heat can be drained to water deposits or ponds in a lower level, through heat i' pipes, being possible to use water tanks, swimming pools (that would have a small heating as aj sub-product), lakes, i rivers, and even the sea. Otherwise!, the water deposit could have a secondary system for its Own refrigeration, by systems utilizing the latent heat of evaporation, as there

;l is no need for larger decreases of temperature. The inventive activity claimed in this document consists of an air conditioning apparatus composed of serpentine heat pipes, comprising an 'upper part set in a region of lower temperature and a lower part set in a environment of higher temperature, with the serpentines being bound by ascending pipes that continue with the ends of the said serpentine e holding inside a refrigerant fluid with a evaporation/condensation point below the temperature of the environment to be cooled and above the temperature of the heat sink.

In the schematic figure, although! the upper serpentine

(condenser) ( C ) is represented in ' a vertical plane, as it not in a tri-dimensional graphic representation, it should preferentially be set in a horizontal plane, in the lower part of the water deposit ! (A) that may have variations of its level. Between the lower serpentine

(evaporator) (E) and the condenser (| C ) the connecting pipes (TA and TB) constitute the adiabatic part of the i apparatus. The lower serpentine (evaporator) (E) is placed in a vertical or almost vertical plane.

A humidity collector, composed in the upper part of a porous material to adsorve water, gOes on to drain it outside the environment (not represented in the figure) . The fins that are added to the serpentines are not expressed in the figure.

Claims

1. AIR CONDITIONING APPARATUS MADE OFlHEAT PIPES, composed of an upper serpentine (condenser) ( Cj) with its pipes and turns in the horizontal plane, in the lower part of a water deposit (A) and of a lower serpentine (evaporator)

(E) immersed in the environment air to be cooled, with its pipes and turns in a vertical or almost vertical plane, and pipes (TA and TB) that connect the upper serpentine with the lower one, that are constituents of the adiabatic part of the apparatus; it is characterized!¹ by holding a working fluid (refrigerant) maintained with its evaporation/condensation point below the temperature of the environment to be cooled and higher than the temperature of the water deposit where the heat should be sent; 2. AIR CONDITIONING APPARATUS MADE OF BEAT PIPES, according

I, to claim 1; it is characterized by; an environment that drains heat, where the condenser is immersed, being a water deposit, the type of water tank jjused in houses and buildings, or water pools; ^; 4. AIR CONDITIONING APPARATUS MADE OF JHEAT PIPES, according to claim 1, it is characterized by evaporator and condenser parts as well as their connecting parts which are composed of parallel series of pulsating (oscillatory) heat pipes.