Preparation method of high-adsorption ammonia refrigerant adsorbent suitable for low-pressure steam

Abstract

This invention relates to the field of adsorbent technology, specifically to a method for preparing a high-adsorption-capacity ammonia refrigeration adsorbent suitable for low-pressure steam, comprising the following steps: Step 1: Raw material formulation optimization and pretreatment, S1.1 Formulation composition (by mass parts): Main adsorbent: 50-60 parts zinc oxide, 20-25 parts aluminum hydroxide, providing core adsorption active sites; This invention adopts a composite formulation of "main adsorbent + activity enhancer + pore structure regulator", which, after directional activation treatment, achieves an ammonia adsorption capacity ≥0.35g / g under low-pressure steam drive (desorption temperature 100℃), which is more than 40% higher than that of traditional adsorbents. This enables a 24,000 Kcal / h ice-making system to produce more than 5 tons of ice per day, making full use of low-pressure steam energy. The optimized preparation process reduces the adsorbent desorption activation energy to 80-90kJ / mol. At a low-pressure steam desorption temperature of 80-120℃, the ammonia desorption rate is ≥95%, and the adsorption capacity retention rate after 5000 cycles is ≥90%, with no significant attenuation.

Description

Technical Field

[0001] This invention relates to the field of adsorbent technology, specifically a method for preparing a high-adsorption-capacity ammonia refrigeration adsorbent suitable for low-pressure steam. Background Technology

[0002] Low-pressure steam (≥0.3MPa) driven ammonia adsorption refrigeration systems are widely used in ice making, cold storage, and cold chain transportation due to their advantages such as zero emissions, low cost, and suitability for industrial waste heat. As the core functional material of the system, the adsorbent's adsorption capacity, low-pressure steam compatibility, and cycle stability directly determine the refrigeration efficiency and service life of the system. Currently, ammonia refrigeration adsorbents suitable for low-pressure steam face several technical challenges:

[0003] Insufficient low-pressure adsorption capacity and low waste heat utilization rate: Traditional adsorbents (such as single zinc oxide and activated carbon) can only adsorb 0.2 to 0.25 g / g of ammonia under low-pressure steam drive (desorption temperature 80~120℃), which cannot make full use of the energy of low-pressure steam, resulting in insufficient cooling capacity of the refrigeration system (such as a 24,000 Kcal / h ice-making system with a daily ice production of less than 4 tons).

[0004] Poor adaptability to low-pressure conditions and incomplete desorption: The heat provided by low-pressure steam is limited, and the traditional adsorbent has a high desorption activation energy. At a desorption temperature of 80~120℃, the ammonia desorption rate is ≤85%. Residual ammonia molecules occupy active sites, resulting in rapid decay of the cyclic adsorption capacity. After 1000 cycles, the adsorption capacity loss is ≥30%.

[0005] Insufficient structural stability and easy agglomeration of powder: Under the alternating circulation of low-pressure steam and cooling water, the adsorbent particles are prone to breakage and agglomeration due to thermal expansion and contraction, resulting in powder spraying, clogging ammonia circuit valves and pipelines, leading to system gas leakage, control failure, and high maintenance costs.

[0006] Weak corrosion resistance and short service life: The trace amounts of sulfides, moisture and other impurities that may be contained in industrial low-pressure steam will react chemically with traditional adsorbents, destroying their crystal structure and active sites, causing the adsorbent to "poison" and fail, with a service life of only 2 to 3 years.

[0007] The preparation process is crude and lacks targeted optimization: the existing adsorbent preparation does not take into account the characteristics of low-pressure steam-driven operation (low-temperature desorption, limited energy, and frequent cycles), and only uses conventional high-temperature calcination and simple mixing processes. This results in a mismatch between the pore structure and active sites of the adsorbent and the low-pressure operation, which restricts the improvement of system performance.

[0008] Existing technologies have not yet formed a dedicated adsorbent preparation system that combines "high adsorption capacity, low pressure compatibility, long cycle life, and resistance to powder spraying." Insufficient adsorption capacity and poor compatibility with low-pressure conditions have become the core bottlenecks restricting the industrialization of low-pressure steam ammonia adsorption refrigeration systems. To address this, a method for preparing high-adsorption-capacity ammonia refrigeration adsorbents suitable for low-pressure steam is proposed. Summary of the Invention

[0009] In view of this, the present invention provides a method for preparing ammonia refrigeration adsorbent with high adsorption capacity suitable for low-pressure steam, so as to solve or alleviate the technical problems existing in the prior art, and at least provide a beneficial alternative.

[0010] The technical solution of this invention is achieved as follows: a method for preparing a high-adsorption-capacity ammonia refrigeration adsorbent suitable for low-pressure steam, comprising the following steps:

[0011] Step 1: Raw material formulation optimization and pretreatment

[0012] S1.1 Formulation composition (by parts by weight):

[0013] Main adsorbent: 50-60 parts zinc oxide and 20-25 parts aluminum hydroxide, providing core adsorption active sites;

[0014] Activity enhancer: 5-8 parts hydroxyapatite and 3-5 parts cerium oxide, which reduce the desorption activation energy and enhance the low-pressure adsorption activity;

[0015] Pore ​​structure regulator: 4-6 parts coconut shell activated carbon and 2-3 parts graphene oxide to optimize pore size distribution and increase specific surface area;

[0016] Binder: 6-10 parts attapulgite, 3-5 parts silica sol, to enhance particle strength and improve dust spray resistance;

[0017] Sintering aid: 1-2 parts boric acid, to lower the sintering temperature and promote the fusion of various components;

[0018] S1.2 Raw material pretreatment:

[0019] Zinc oxide, aluminum hydroxide, hydroxyapatite, and cerium oxide were pulverized to a particle size ≤40μm and dried at 120℃ for 3-4 hours to remove moisture and impurities.

[0020] Coconut shell activated carbon is treated with acid (5% hydrochloric acid solution, soaked at 60℃ for 2-3 hours), washed until neutral, and then dried to enhance its adsorption activity.

[0021] Attapulgite clay is calcined at 800℃ for 1.5–2 hours to activate its bonding properties;

[0022] Step 2: Composite Mixing and Granulation

[0023] S2.1 Premixing: Weigh all solid components according to the formula, add them to a high-speed mixer, and mix for 30 to 40 minutes at a speed of 1000 to 1200 r / min to obtain a homogeneous solid mixture;

[0024] S2.2 Modification and Mixing: Add deionized water (solid-liquid mass ratio 1:0.4~0.6) and surface modifier (silane coupling agent KH-5601~2 parts) to the solid mixture, and continue stirring for 20~30 minutes to make the modifier uniformly coat the particle surface;

[0025] S2.3 Granulation and Molding: The mixture is fed into a spherical granulator at a speed of 350~450 r / min, and the granulation particle size is controlled at 1~2 mm to obtain spherical wet granules; then it is placed in an oven and dried at 110~120℃ for 6~8 hours until the moisture content is ≤3%;

[0026] Step 3: Segmented calcination and directional activation

[0027] S3.1 Segmented Calcination: The dried granules are fed into a rotary kiln for segmented temperature-controlled calcination.

[0028] Low temperature range: 250~300℃, keep warm for 2~3 hours to remove residual moisture and organic matter;

[0029] Medium temperature range: 550~650℃, heat preservation for 3~4 hours, to promote the reaction between binder and sintering aid and enhance particle strength;

[0030] High temperature section: 850~950℃, heat preservation for 4~5h, to achieve solid-phase reaction of each component and form a stable crystal structure;

[0031] S3.2 Directional activation: After calcination, the adsorbent is naturally cooled to 300~350℃, and a mixture of ammonia and nitrogen (volume ratio 1:5) is purged for 2~3 hours at a flow rate of 10~15L / min to activate the ammonia adsorption active sites on the surface of the adsorbent; then it is cooled to room temperature to obtain a high-adsorption-capacity ammonia refrigeration adsorbent product.

[0032] Step 4: Performance Testing and Screening

[0033] S4.1 Physical and chemical performance testing: Test the specific surface area (≥250m² / g), pore size distribution (micropores + mesopores ≥80%), compressive strength (≥18MPa), and wear rate (≤0.3%) of the finished product.

[0034] S4.2 Adsorption performance test: Under the conditions of desorption temperature of 100℃, adsorption temperature of 40℃, and low-pressure steam pressure of 0.3MPa, the ammonia adsorption capacity (≥0.35g / g) and desorption rate (≥95%) were tested.

[0035] S4.3 Stability test: After 5000 adsorption-desorption cycles, the adsorption capacity retention rate (≥90%) and specific surface area loss rate (≤8%) were tested.

[0036] S4.4 Screening and Warehousing: After all performance indicators meet the standards, qualified finished products are screened and put into the warehouse for future use.

[0037] More preferably, the mass ratio of the main adsorbent zinc oxide to aluminum hydroxide in step S1.1 is 2.5:1. At this ratio, the adsorbent has the largest adsorption capacity for ammonia and the lowest desorption activation energy.

[0038] More preferably, the concentration of the hydrochloric acid solution used in step S1.2 is 5%, and the soaking temperature is 60°C, which can effectively remove impurities from coconut shell activated carbon and increase the specific surface area by ≥30%.

[0039] More preferably, the mass ratio of the surface modifier silane coupling agent KH-560 to the solid mixture in step S2.2 is 0.02:1, which can significantly improve the bonding strength and corrosion resistance of the adsorbent particles.

[0040] In a further preferred embodiment, the heating rate of the rotary kiln in step S3.1 is controlled at 5~8℃ / min to avoid excessive heating that could cause particle cracking; the calcination atmosphere is an air atmosphere to ensure that all components react fully.

[0041] Further preferably, the mixed gas for directional activation in step S3.2 is ammonia and nitrogen in a volume ratio of 1:5, which can specifically activate the ammonia adsorption active sites and increase the low-pressure adsorption capacity.

[0042] In a further preferred embodiment, the wear rate detection in step S4.1 adopts the tumbling wear method, in which the adsorbent particles are placed in a wear tester, the rotation speed is 600 r / min, the test time is 2h, and the wear rate is calculated.

[0043] More preferably, the desorption activation energy of the adsorbent is 80~90kJ / mol, which is suitable for an ammonia adsorption refrigeration system driven by low-pressure steam of 0.3~0.8MPa.

[0044] The embodiments of the present invention have the following advantages due to the adoption of the above technical solutions:

[0045] I. This invention employs a composite formulation of "main adsorbent + activity enhancer + pore structure regulator". After directional activation treatment, the ammonia adsorption capacity of the adsorbent under low-pressure steam drive (desorption temperature 100℃) is ≥0.35g / g, which is more than 40% higher than that of traditional adsorbents. This enables a 24,000 Kcal / h ice-making system to produce more than 5 tons of ice per day. It makes full use of low-pressure steam energy, optimizes the preparation process to reduce the adsorbent desorption activation energy to 80~90kJ / mol, and achieves an ammonia desorption rate of ≥95% at a low-pressure steam desorption temperature of 80~120℃. After 5000 cycles, the adsorption capacity retention rate is ≥90%, with no significant attenuation.

[0046] II. Through high-temperature sintering and surface coating treatment, the adsorbent particles have a compressive strength ≥18MPa and an wear rate ≤0.3%. There is no cracking or powder spraying during cyclic use, which can avoid valve blockage and pipeline wear. The system can run continuously for ≥8000 hours. The dense protective film formed by the surface coating can resist the erosion of trace sulfides and moisture in low-pressure steam. The adsorbent has a stable crystal structure and good reversibility of complexation reaction with ammonia, extending its service life to 8-10 years and significantly reducing system maintenance costs.

[0047] Third, the preparation process of this invention is precisely matched with the low-pressure steam ammonia adsorption and refrigeration conditions. It adopts processes such as segmented calcination and directional activation, which do not require special high-end equipment. The production cost is reduced by 15% to 20% compared with traditional adsorbents, making it suitable for industrial mass production.

[0048] The above overview is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of the invention will become readily apparent from the accompanying drawings and the following detailed description. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0050] Figure 1 This is a flowchart of the preparation method of the present invention. Detailed Implementation

[0051] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0052] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0053] like Figure 1 As shown, this embodiment of the invention provides a method for preparing a high-adsorption-capacity ammonia refrigeration adsorbent suitable for low-pressure steam, comprising the following steps:

[0054] Step 1: Raw material formulation optimization and pretreatment

[0055] S1.1 Formulation composition (by parts by weight):

[0056] Main adsorbent: 50-60 parts zinc oxide and 20-25 parts aluminum hydroxide, providing core adsorption active sites;

[0057] Activity enhancer: 5-8 parts hydroxyapatite and 3-5 parts cerium oxide, which reduce the desorption activation energy and enhance the low-pressure adsorption activity;

[0058] Pore ​​structure regulator: 4-6 parts coconut shell activated carbon and 2-3 parts graphene oxide to optimize pore size distribution and increase specific surface area;

[0059] Binder: 6-10 parts attapulgite, 3-5 parts silica sol, to enhance particle strength and improve dust spray resistance;

[0060] Sintering aid: 1-2 parts boric acid, to lower the sintering temperature and promote the fusion of various components;

[0061] S1.2 Raw material pretreatment:

[0062] Zinc oxide, aluminum hydroxide, hydroxyapatite, and cerium oxide were pulverized to a particle size ≤40μm and dried at 120℃ for 3-4 hours to remove moisture and impurities.

[0063] Coconut shell activated carbon is treated with acid (5% hydrochloric acid solution, soaked at 60℃ for 2-3 hours), washed until neutral, and then dried to enhance its adsorption activity.

[0064] Attapulgite clay is calcined at 800℃ for 1.5–2 hours to activate its bonding properties;

[0065] Step 2: Composite Mixing and Granulation

[0066] S2.1 Premixing: Weigh all solid components according to the formula, add them to a high-speed mixer, and mix for 30 to 40 minutes at a speed of 1000 to 1200 r / min to obtain a homogeneous solid mixture;

[0067] S2.2 Modification and Mixing: Add deionized water (solid-liquid mass ratio 1:0.4~0.6) and surface modifier (silane coupling agent KH-5601~2 parts) to the solid mixture, and continue stirring for 20~30 minutes to make the modifier uniformly coat the particle surface;

[0068] S2.3 Granulation and Molding: The mixture is fed into a spherical granulator at a speed of 350~450 r / min, and the granulation particle size is controlled at 1~2 mm to obtain spherical wet granules; then it is placed in an oven and dried at 110~120℃ for 6~8 hours until the moisture content is ≤3%;

[0069] Step 3: Segmented calcination and directional activation

[0070] S3.1 Segmented Calcination: The dried granules are fed into a rotary kiln for segmented temperature-controlled calcination.

[0071] Low temperature range: 250~300℃, keep warm for 2~3 hours to remove residual moisture and organic matter;

[0072] Medium temperature range: 550~650℃, heat preservation for 3~4 hours, to promote the reaction between binder and sintering aid and enhance particle strength;

[0073] High temperature section: 850~950℃, heat preservation for 4~5h, to achieve solid-phase reaction of each component and form a stable crystal structure;

[0074] S3.2 Directional activation: After calcination, the adsorbent is naturally cooled to 300~350℃, and a mixture of ammonia and nitrogen (volume ratio 1:5) is purged for 2~3 hours at a flow rate of 10~15L / min to activate the ammonia adsorption active sites on the surface of the adsorbent; then it is cooled to room temperature to obtain a high-adsorption-capacity ammonia refrigeration adsorbent product.

[0075] Step 4: Performance Testing and Screening

[0076] S4.1 Physical and chemical performance testing: Test the specific surface area (≥250m² / g), pore size distribution (micropores + mesopores ≥80%), compressive strength (≥18MPa), and wear rate (≤0.3%) of the finished product.

[0077] S4.2 Adsorption performance test: Under the conditions of desorption temperature of 100℃, adsorption temperature of 40℃, and low-pressure steam pressure of 0.3MPa, the ammonia adsorption capacity (≥0.35g / g) and desorption rate (≥95%) were tested.

[0078] S4.3 Stability test: After 5000 adsorption-desorption cycles, the adsorption capacity retention rate (≥90%) and specific surface area loss rate (≤8%) were tested.

[0079] S4.4 Screening and Warehousing: After all performance indicators meet the standards, qualified finished products are screened and put into the warehouse for future use.

[0080] In one embodiment, the mass ratio of the main adsorbent zinc oxide to aluminum hydroxide in step S1.1 is 2.5:1. At this ratio, the adsorbent has the largest adsorption capacity for ammonia and the lowest desorption activation energy.

[0081] In one embodiment, the concentration of the hydrochloric acid solution in step S1.2 is 5%, and the soaking temperature is 60°C, which can effectively remove impurities from coconut shell activated carbon and increase the specific surface area by ≥30%.

[0082] In one embodiment, the mass ratio of the surface modifier silane coupling agent KH-560 to the solid mixture in step S2.2 is 0.02:1, which can significantly improve the bonding strength and corrosion resistance of the adsorbent particles.

[0083] In one embodiment, the heating rate of the rotary kiln in step S3.1 is controlled at 5~8℃ / min to avoid excessive heating that could cause particle cracking; the calcination atmosphere is an air atmosphere to ensure that all components react fully.

[0084] In one embodiment, the mixed gas for targeted activation in step S3.2 is ammonia and nitrogen in a volume ratio of 1:5, which can specifically activate the ammonia adsorption active sites and increase the low-pressure adsorption capacity.

[0085] In one embodiment, the wear rate detection in step S4.1 adopts the tumbling wear method, in which the adsorbent particles are placed in a wear tester, the rotation speed is 600 r / min, the test time is 2h, and the wear rate is calculated.

[0086] In one embodiment, the desorption activation energy of the adsorbent is 80~90kJ / mol, which is suitable for an ammonia adsorption refrigeration system driven by low-pressure steam of 0.3~0.8MPa.

[0087] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various variations or substitutions within the technical scope disclosed in the present invention, and these should all be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a high-adsorption-capacity ammonia refrigerant adsorbent suitable for low-pressure steam, characterized in that: Includes the following steps: Step 1: Raw material formulation optimization and pretreatment S1.1 Formulation composition (by parts by weight): Main adsorbent: 50-60 parts zinc oxide and 20-25 parts aluminum hydroxide, providing core adsorption active sites; Activity enhancer: 5-8 parts hydroxyapatite and 3-5 parts cerium oxide, which reduce the desorption activation energy and enhance the low-pressure adsorption activity; Pore ​​structure regulator: 4-6 parts coconut shell activated carbon and 2-3 parts graphene oxide to optimize pore size distribution and increase specific surface area; Binder: 6-10 parts attapulgite, 3-5 parts silica sol, to enhance particle strength and improve dust spray resistance; Sintering aid: 1-2 parts boric acid, to lower the sintering temperature and promote the fusion of various components; S1.2 Raw material pretreatment: Zinc oxide, aluminum hydroxide, hydroxyapatite, and cerium oxide were pulverized to a particle size ≤40μm and dried at 120℃ for 3-4 hours to remove moisture and impurities. Coconut shell activated carbon is treated with acid (5% hydrochloric acid solution, soaked at 60℃ for 2-3 hours), washed until neutral, and then dried to enhance its adsorption activity. Attapulgite clay is calcined at 800℃ for 1.5–2 hours to activate its bonding properties; Step 2: Composite Mixing and Granulation S2.1 Premixing: Weigh all solid components according to the formula, add them to a high-speed mixer, and mix for 30 to 40 minutes at a speed of 1000 to 1200 r / min to obtain a homogeneous solid mixture; S2.2 Modification and Mixing: Add deionized water (solid-liquid mass ratio 1:0.4~0.6) and surface modifier (silane coupling agent KH-5601~2 parts) to the solid mixture, and continue stirring for 20~30 minutes to make the modifier uniformly coat the particle surface; S2.3 Granulation and Molding: The mixture is fed into a spherical granulator at a speed of 350~450 r / min, and the granulation particle size is controlled at 1~2 mm to obtain spherical wet granules; then it is placed in an oven and dried at 110~120℃ for 6~8 hours until the moisture content is ≤3%; Step 3: Segmented calcination and directional activation S3.1 Segmented Calcination: The dried granules are fed into a rotary kiln for segmented temperature-controlled calcination. Low temperature range: 250~300℃, keep warm for 2~3 hours to remove residual moisture and organic matter; Medium temperature range: 550~650℃, heat preservation for 3~4 hours, to promote the reaction between binder and sintering aid and enhance particle strength; High temperature section: 850~950℃, heat preservation for 4~5h, to achieve solid-phase reaction of each component and form a stable crystal structure; S3.2 Directional activation: After calcination, the adsorbent is naturally cooled to 300~350℃, and a mixture of ammonia and nitrogen (volume ratio 1:5) is purged for 2~3 hours at a flow rate of 10~15L / min to activate the ammonia adsorption active sites on the surface of the adsorbent; then it is cooled to room temperature to obtain a high-adsorption-capacity ammonia refrigeration adsorbent product. Step 4: Performance Testing and Screening S4.1 Physical and chemical performance testing: Test the specific surface area (≥250m² / g), pore size distribution (micropores + mesopores ≥80%), compressive strength (≥18MPa), and wear rate (≤0.3%) of the finished product. S4.2 Adsorption performance test: Under the conditions of desorption temperature of 100℃, adsorption temperature of 40℃, and low-pressure steam pressure of 0.3MPa, the ammonia adsorption capacity (≥0.35g / g) and desorption rate (≥95%) were tested. S4.3 Stability test: After 5000 adsorption-desorption cycles, the adsorption capacity retention rate (≥90%) and specific surface area loss rate (≤8%) were tested. S4.4 Screening and Warehousing: After all performance indicators meet the standards, qualified finished products are screened and put into the warehouse for future use.

2. The method for preparing a high-adsorption-capacity ammonia refrigeration adsorbent suitable for low-pressure steam according to claim 1, characterized in that: In step S1.1, the mass ratio of the main adsorbent zinc oxide to aluminum hydroxide is 2.5:

1. At this ratio, the adsorbent has the largest adsorption capacity for ammonia and the lowest desorption activation energy.

3. The method for preparing a high-adsorption-capacity ammonia refrigeration adsorbent suitable for low-pressure steam according to claim 1, characterized in that: The hydrochloric acid solution concentration for acid treatment in step S1.2 is 5%, and the soaking temperature is 60℃, which can effectively remove impurities from coconut shell activated carbon and increase the specific surface area by ≥30%.

4. The method for preparing a high-adsorption-capacity ammonia refrigeration adsorbent suitable for low-pressure steam according to claim 1, characterized in that: The surface modifier silane coupling agent KH-560 mentioned in step S2.2 has a mass ratio of 0.02:1 to the solid mixture, which can significantly improve the bonding strength and corrosion resistance of the adsorbent particles.

5. The method for preparing a high-adsorption-capacity ammonia refrigerant adsorbent suitable for low-pressure steam according to claim 1, characterized in that: In step S3.1, the heating rate of the rotary kiln is controlled at 5~8℃ / min to avoid excessive heating that could cause particle cracking; the calcination atmosphere is air to ensure that all components react fully.

6. The method for preparing a high-adsorption-capacity ammonia refrigeration adsorbent suitable for low-pressure steam according to claim 1, characterized in that: In step S3.2, the mixed gas for directional activation is ammonia and nitrogen in a volume ratio of 1:5, which can specifically activate the ammonia adsorption active sites and increase the low-pressure adsorption capacity.

7. The method for preparing a high-adsorption-capacity ammonia refrigerant adsorbent suitable for low-pressure steam according to claim 1, characterized in that: In step S4.1, the wear rate is detected using the tumbling wear method. The adsorbent particles are placed in the wear tester, the rotation speed is 600 r / min, the test time is 2 hours, and the wear rate is calculated.

8. The method for preparing a high-adsorption-capacity ammonia refrigerant adsorbent suitable for low-pressure steam according to claim 1, characterized in that: The desorption activation energy of the adsorbent is 80~90kJ / mol, which is suitable for ammonia adsorption refrigeration systems driven by low-pressure steam of 0.3~0.8MPa.

Images