Description ADSORPTION COOLING APPARATUS, MANUFACTURING AND

OPERATING METHOD

Technical Field

[I] The present invention relates to an adsorption cycle apparatus suitable for cooling and powered by low grade thermal energy .

[2] The apparatus of the invention operates at low pressure using an adsorbent/adsorbate

(micropourous solid/fluid) pair with limited risk for the environment and human health.

[3] Furthermore, the invention discloses a manufacturing method embodied in a novel form of surfaces assemblying, avoiding valves or isolated components connected by the means of piping like prior art Background Art

[4] For many years adsorption refrigeration has been studied as an alternative to conventional vapour compression refrigeration systems, which are far way from ecologically sustainable due to their green house gas emissions and electrical power consumptions.

[5] Prior art teaches a few solutions in which the adsorption cycle is run at low pressure using Silica-Gel/water, zeolite/water [(EP 1788 324), WO 93/13368, DE 1023762 WO03/ 071197, US5964097] but all of them are based on layouts with several separated components (Evaporator, condensator and reactor) connected by means of piping and valves and with a very low COP (Coefficient of Performance). Disclosure of Invention Technical Problem

[6] The prior art efficiency is limited due to the low amount of mass transferred from/to each seperated component (evaporator, condensator and reactor) due to the use of valves and piping at low pressures conditions .

[7] Prior Art form of assembly also increases the heat input needs, in order to impose different temperatures in the adsorbent medium (micropourus solid) and also presents problems due to low pressure (below atmospheric pressure) control/maintenance. Technical Solution

[8] In the study (Adsorption Cycle Modeling: Characterization and comparison of materials) made by Tomas Nunez, Hans-Martin Henning, Walter Mittelbach for the Fraunhofer Institut, a single curve is proposed to describe the level of adsorvate content on the adsorbent (W) of the cycle, as function of the differential potential work of adsorption (A) :

[9] W = f(A) [l]

[10] Where

[II] A = r T ln(Ps(T)/p) [2]

[12] For desorption purposes (Heat input in the cycle) the efficient way to reach a lower level of adsorbate (fluid to be evaporated/condensed) content in the adsorbent (W) is to maximize the Potential work of Adsorption (A).

[13] We can notice in the equation 2 that there is no advantage gained by increasing the pressure (p) during the desorption stage, nor by the use of valves nor by piping inside of the reservoir , like other apparatuses of prior art propose [(EP 1788 324), WO 93/13368, DE 1023762], such components lead to a lower COP and longer cycles times and low mass transfer between each separated component(Reactor, Evaporator and Condensator) on their designs.

[14] A single, monocoque reservoir [Fig.l] can have distinct surfaces temperatures inside of it due to the low heat transfer (conduction and radiation) between those different surfaces inside a closed reservoir and to the low pressure condition on near absolute vacuum . Advantageous Effects

[15] The condensation will be driven only by the difference in surface temperatures and not by pressure changes like the cycles known from prior art.

[16] This single reservoir (monocoque) system of the invention will allow a quicker regeneration of the adsorbent ,it will also improve the mass transfer of the adsorbate for the evaporation/condensation purposes and will reduce cycle times due to the greater mass transfer inside of the reservoi, leading to an increase of the COP of such apparatus. Description of Drawings

[17] Figure 1 is an illustration of the possible combination of different surfaces in order to provide two closed reservoires where the adsorption cycle can be operated as follows.

[18] A mean temperature fluid with a temperature greater than of the evaporator and lower than the reacting surface at desorption stage defined here as Tm, is passed inside the reacting surface (2), this reacting surface can be a metallic or any good heat transfer material in order to cool the adsorbent (5).

[19] The adsorbent that can be a microporous solid like silica-gel, zeolites or active carbon will -according to the equations [1] and [2] - start to adsorb the gaseous molecules of the adsorbate [5] leading to the evaporation of the liquid state adsorbate positioned above the evaporating surface (4) thus providing a refrigerating effect needed for cooling and to lower the specific temperature of the evaporating surface (3).

[20] Surface 3 must be made of a good heat transfer property material, like copper or aluminium or any metallic material.

[21] The adsorbent [5] will then reach its saturation point, at which the evaporation stops.

[22] Hot fluid is now passed between the reacting surfaces [2] that preferably are as thin as possible in order to reduce the heat needed to elevate the adsorbent/reacting surfaces pairs [5 and 2] .

[23] Elevating the temperature of the adsorbent will cause the desorption effect to start

and gaseous molecules are then released from the adsorbent.

[24] Condensation surfaces (1) are maintained at a constant mean temperature Tm, lower than the adsorbent (5) temperature during the described desorption phase. This surface (1) can be made of glass , metallic or any material that leads to a good surface condensation medium .

[25] The surface (1) ideally must have greater area in relation to the other surfaces , to cause the gaseous molecules released from the adsorbent to reach quicker this surface in order to be condensated and slide to the evaporating surface fluid (4),

[26] The condensation phenomena will stop when the adsorbent (5) reaches its equilibrium point due to its surface temperature (Td - highest temperature in the cycle)

[27] Cold fluid is now passed though the apertures of the reacting surfaces in order to bring the adsorbent temperature back to Tm and the cycle of the invention is repeated again.

[28] To achieve a continuous mode of refrigeration effect, two or more monocoques apparatuses can be run alternately.

[29] The surfaces l,3and 5 are in no direct contact with each others, and are separated by plastic or any other similar material with good thermal isolation properties. Industrial Applicability

[30] 1. - air conditioning for domestic, industrial and motorized vehicles purpose.

2. - cooling systems for engines, blowers

3. - chilled water production