Hydrogen-hydride absorption systems and methods for refrigeration and heat pump cycles

A method for deriving refrigeration from a hydrogen absorption system which includes two subsystems each containing a plurality of hydride-dehydride reactors, which method comprises:

• combining hydrogen gas with a first hydride-forming material in a reactor of one of said subsystems under conditions of a temperature, T.sub.1, and a pressure, P.sub.1, such that a first hydride saturated with, and in equilibrium with, hydrogen gas is formed, as the thus combined hydrogen gas is desorbed from a second hydride in a reactor of the second subsystem at a refrigeration temperature, T.sub.2, lower than T.sub.1, and a pressure, P.sub.2, slightly greater than P.sub.1, wherein the heat necessary to desorb the second hydride is the refrigeration load;
• concurrently heating the first and second hydrides at constant volume by recovering sensible heat from a different reactor in their respective subsystems;
• then
• further heating the first hydride at constant volume to a temperature, T.sub.3, and a pressure, P.sub.3, which are substantially higher than T.sub.1 and P.sub.1 ;
• and
• further heating the second hydride at constant volume to a temperature, T.sub.1, and a pressure slightly lower than P.sub.3 ;
• heating the first hydride to desorb hydrogen gas at a temperature, T.sub.3, and a pressure, P.sub.3 ;
• absorbing the last-mentioned desorbed hydrogen gas in the hydridable material derived from said second hydride;
• concurrently cooling the first and second hydrides at constant volume by transferring heat to a reactor in each of the respective subsystems;
• further cooling the first hydride at constant volume by a heat exchange fluid;
• cooling the second hydride by dehydriding the second hydride by desorption of hydrogen therefrom;
• and
• cyclically repeating the foregoing steps.

A method for deriving a heat pump effect from a hydrogen absorption system comprising:

• combining hydrogen gas with a first hydride-forming material under conditions of temperature, T.sub.1, and pressure, P.sub.1, such that a first hydride saturated with and in equilibrium with hydrogen gas is formed as the hydrogen gas is desorbed from a second hydride at a temperature, T.sub.2, substantially lower than T.sub.1, and a pressure, P.sub.2, slightly greater than P.sub.1, wherein the heat of absorption of the first hydride is the heat pump effect;
• partial cooling of the first and second hydrides at constant volume by transferring heat to a reactor in each of their respective systems;
• further cooling the first hydride by desorption;
• cooling the second hydride at constant volume by a heat exchange fluid;
• heating the first hydride to desorb hydrogen gas at a temperature, T.sub.2, and a pressure, P.sub.4, substantially lower than P.sub.1, and combining the hydrogen gas in the second hydride-forming material at a temperature, T.sub.3, substantially lower than T.sub.2, and a pressure, P.sub.3, slightly lower than P.sub.4 ;
• partially heating the first and second hydrides at constant volume by recovering heat from a reactor in their respective systems;
• further heating the first hydride by absorption;
• heating the second hydride at constant volume to the temperature, T.sub.2, and pressure, P.sub.2 ;
• and
• cyclically repeating the foregoing steps.

A method for deriving refrigeration from a hydrogen absorption system comprising:

• establishing a first group of first reaction zones having a first hydridable material in at least one of said first reaction zones, and a hydride formed from said first hydridable material in another of said first reaction zones;
• establishing a second group of second reaction zones having a second hydridable material in at least one of said second reaction zones, and a hydride formed from said second hydridable material in at least one other of said second reaction zones, said second hydridable material having a capability of producing an equilibrium pressure of hydrogen higher than the equilibrium pressure of hydrogen produced by said first hydridable material in said first reaction zones when both said first and second hydridable materials are at the same equilibrium temperature;
• transferring heat from a refrigeration medium to the one of said second reaction zones containing the hydride of said second hydridable material to desorb hydrogen gas therefrom at a refrigeration temperature T.sub.2, and in a pressure P.sub.2, wherein the heat necessary to desorb hydrogen gas from the hydride of the second hydridable material is the refrigeration load;
• transferring desorbed hydrogen gas from said second reaction zone containing a hydride of said second hydridable material undergoing desorption of the hydrogen gas from the hydride therein by the cooling of said refrigeration medium, to the first hydridable material in said one of said first reaction zones;
• combining said transferred hydrogen gas with said first hydridable material in said one of said first reaction zones under conditions of a temperature, T.sub.1, and a pressure, P.sub.1, which is less than P.sub.2, such that a hydride of said first hydridable material in said one first reaction zone which is saturated with, and in equilibrium with, hydrogen gas is formed with concurrent exothermal release of thermal energy;
• then
• concurrently increasing the temperature of the desorbed material in said one other of said second reaction zones, and concurrently, increasing the temperature of the hydride material formed in said one first reaction zone by the use of sensible heat supplied from a second of the reaction zones in the respective groups in which said one other of said second reaction zones, and said one of said first reaction zones are located;
• further heating the hydride of said first hydridable material at constant volume to a temperature, T.sub.3, and a pressure, P.sub.3, which temperature, T.sub.3, and pressure, P.sub.3, are higher than T.sub.1 and P.sub.1, respectively.
• further heating the hydride of the second hydridable material in said one other of said second reaction zones at constant volume to a temperature, T.sub.1, and a pressure lower than P.sub.3 ;
• terminating the constant volume restriction on the hydride of said first hydridable material in said one reaction zone of said first group and concurrently desorbing hydrogen gas therefrom by continuing to heat the hydride of said first hydridable material in said one reaction zone of said first group at a temperature, T.sub.3, and pressure, P.sub.3, with concurrent volumetric expansion of the desorbed hydrogen gas;
• transferring the desorbed hydrogen gas from said one reaction zone of said first group of reaction zones to the second hydridable material in said one other reaction zone of said second group of reaction zones;
• combining said last-mentioned transferred hydrogen gas with said second hydridable material in said other reaction zone of said second group and maintaining an equilibrium pressure lower than P.sub.3 by transferring heat to an external heat exchange medium, to increase the temperature in said one other reaction zone of said second group while retaining constant volume in said one other reaction zone;
• then
• concurrently decreasing the temperature of the materials in said one reaction zone of said first group, and in said one other reaction zone of said second group by transferring sensible heat therefrom to a different one of the respective first and second reaction zones in the respective first and second groups containing said one reaction zone and said one other reaction zone;
• further cooling the material in said one reaction zone of said first group while retaining said one reaction zone at constant volume;
• further cooling the material in said one other reaction zone of said second group by desorbing hydrogen gas from the material therein;
• and
• cyclically repeating the foregoing steps.