NATIONAL RESEARCH COUNCIL OF ITALY Institute for Advanced Energy Technologies “Nicola Giordano” Thermally driven adsorption heat pumps: recent advancements and future technical challenges Giovanni Restuccia Problématiques Scientifiques et Technologiques dans les Procédés Frigorifiques et Thermiques à Sorption Paris 7/2/2014 SUMMARY Basics Current market Situation R&D priorities Novel Adsorbent Materials Adsorbent coatings Adsorption machine components Machine optimization and control Recent advancement at CNR-ITAE SUMMARY Basics Current market Situation R&D priorities Novel Adsorbent Materials Adsorbent coatings Adsorption machine components Machine optimization and control Recent advancement at CNR-ITAE Thermally Driven ADsorption Machines OPERATING PRINCIPLE Condenser Condenser Bed 1 Bed 2 Bed 1 Bed 2 Evaporator Evaporator Condenser Condenser Bed 1 Bed 2 Bed 1 Bed 2 Evaporator Evaporator Thermally Driven ADsorption Machines PERFOMANCE AND DRAWBACKS Less studied and developed than liquid sorption Not a mature technology Few products on the market Can be efficiently driven by a heat source at a temperature as low as 60- 80 °C Environmental friendly refrigerants (water) Silent operation APPLICATIONS CHP units, process heat Solar collectors District heating Automotive waste heat HEAT SOURCES FOR ADSORPTION CHILLERS o (Low-grade) waste heat recovery o Tri-generation o Air conditioning in vehicles or boats o Solar cooling SUMMARY Basics Current market Situation R&D priorities Novel Adsorbent Materials Adsorbent coatings Adsorption machine components Machine optimization and control Recent advancement at CNR-ITAE Brief history of adsorption chiller development 2000 – today reliable products developed (better heat transfer quality, materials, controls) 1990 – 2000 No commercial products strong enough to survive, apart the Mycom silica gel /water chiller 1980 – 1990 Early studies and prototypes Meunier, Guilleminot, Pons et al. in Paris (AC/Meth, Zeolite/H2O) Tchernev in USA (zeolite/water) Shelton in USA (AC/Ammonia) Spinner in Perpignan (hygroscopic salts) Cacciola and Restuccia in Italy (zeolite/water) Groll in Germany (metal hydrides) Alefeld in Germany (zeolite/water) Current market situation SMALL SIZE UNITS SWAC-10 chiller water-fired silica gel/water 10 kW China Current market situation SMALL SIZE UNITS AQSOA chiller water-fired zeolite/water 10 kW Japan Current market situation HIGH-CAPACITY CHILLERS AdRef-Noa chiller water-fired zeolite/water 105kW - 430kW Japan Ad3 chiller water-fired silica gel/water 35 to 600 kW USA Current market situation COMPARISON The current market for solid sorption heat pumps is very small, due to: • High capital costs • Still too big and too heavy to compete with conventional systems • Lower thermal efficiency and power density than liquid sorption systems Advanced prototypes realized at: Warwick University (UK) ECN (NL) SJTU (Ch) CNR ITAE (IT) Adsorption chillers/heat pumps development MAIN ACTORS INVOLVED ASIA SUMMARY Basics Current market Situation R&D priorities Novel Adsorbent Materials Adsorbent coatings Adsorption machine components Machine optimization and control Recent advancement at CNR-ITAE Future challenges Today a limited number of materials is used! Materials New or modified adsorbents needed Stability over several thousand cycles Compact, lightweight, high surface area HEXs and adsorbent reactors Compact and low cost evaporator and condenser Components for adsorption machines Coated adsorbent reactors Machine optimization control & integration Advanced control strategies Compact and modular system designs SUMMARY Basics Current market Situation R&D priorities Novel Adsorbent Materials Adsorbent coatings Adsorption machine components Machine optimization and control Recent advancement at CNR-ITAE Development of advanced adsorbent materials The adsorbent material is a key-element of an adsorption machine Initially, adsoption heat transformers were realized using not optimized adsorbents (Zeolite 4A, X, silica gel) New generation of adsorption machines requires novel adsorbent materials with optimal adsorption properties Tdes ∆W = ∆W Tads “New” adsorbent materials Composite Adsorbents «salt in matrix» (Selective Water Sorbents) Modified Zeolites (dealuminated zeolites, MeAPO) Metallic Organic Frameworks (MOFs) (Major trend) The solution must be stable and cheap. Classical zeolites (4A, 13X, DDZ 70 UOP) Aluminophosphates (SAPO34, AQSOA FAMZ02 from MITSUBISHI Plastics) Microporous silica gel (e.g. Fuji Davison type RD) Porous Carbons (ammonia and alchools adsorbate) SWS-Selective Water Sorbents INITIAL STATE porous host matrix impregnated anhydrous salt solid crystalline hydrates Q <salt> + H2O sorption Q <salt> ∙ n <sorbate> + H2O sorption - H2O desorption + H2O sorption n <sorbate> FINAL STATE solid crystalline hydrates salt aqueous solution <sorbate> = water, methanol, ethanol, ammonia Ca(NO3)2 + 2 H2O = Ca(NO3)2∙2H2O BaBr2 + 8 NH3 = BaBr2∙8NH3 LiCl + 3 CH3OH = LiCl∙3CH3OH LiBr + 3 C2H5OH = LiBr∙3C2H5OH SWS-Selective Water Sorbents SORPTION CHARACTERISTICS MOF-Metall Organic Frameworks MOF-Metall Organic Frameworks Commercially available MOFs: (BASF - Basolite®) Oxygen Carbon Hydrogen Copper Basolite C300 (HKUST-1) structure Basolite® C300 (HKUST-1): Copper-based MOF, trimesate trianions as linkers. It is also known as Cu(BTC). Basolite® F300: Iron-based MOF, trimesate trianions as linkers. Particle size distribution 15.96 μm Particle size distribution ~ 20 μm Surface area BET surf. area 15002100 m2/g Surface area BET surf. area 13001600 m2/g Bulk density 0.35 g/cm3 Bulk density 0.35 g/cm3 Cost ~ 95 €/(10 g) Cost ~ 85 €/(10 g) MOF-Metall Organic Frameworks STABILITY ISSUE 30 27.5 Water Uptake [wt.%] 25 ∆W = - 6 wt % 22.5 BASOLITE C-300: Water adsorption capacity reduction after 5 ad/desorption steps! 20 17.5 15 12.5 10 7.5 5 2.5 0 20 30 40 50 60 70 80 90 100 110 120 130 140 150 Temperature [ C] Ba solite C-300 Ba sf 9.9 mbar Ads. 1 Basolite C-300 Basf 9.9 mba r Ads. 2 Ba solite C-300 Ba sf 10.1 mba r Ads. 4 Basolite C-300 Basf 10.1 mbar Ads. 5 Ba solite C-300 Ba sf 10 mbar Ads. 3 160 Database of Adsorbent Materials A DATABASE of adsorbent materials was created within the IEA - Annex 34 “Thermally Driven Heat Pumps for Heating and Cooling” Databasing of adsorbents is continuing within the new Annex 43 “fuel driven sorption heat pumps”. 30 27.5 25 Water Uptake [wt.%] 22.5 20 17.5 15 12.5 10 7.5 5 2.5 0 20 40 60 80 100 120 140 160 180 Temperature [°C] AQSOA-FAMZ02 11.8 mbar UOP DDZ70 10.8 mbar Tiajin SAPO 34 11 mbar Union Carbide Na-Y 12.2 mbar Fuji Davidson 12 mbar Oker Chemie Silica Gel Siogel 10 mbar Zeolyst CBV-100 10.7 mbar BASF Basolite C300 9.9 mbar BASF Basolite F300 9.8 mbar 200 Overall comparison of adsorbents Material Ability to be regenerated at low T Maximum adsorption capacity Hydrothermal stability AQSOA – Z02 + + + NaY UnionCarbide - + + NaY CBV-100 - + + DDZ70 - + + Fuji Davidson + - + Basolite C300 + + - SAPO 34 + + - Siogel + - + Basolite F300 + - - AQSOA Z02 is the best material for low T application SUMMARY Basics Current market Situation R&D priorities Novel Adsorbent Materials Adsorbent coatings Adsorption machine components Machine optimization and control Recent advancement at CNR-ITAE Coated adsorbers HEAT TRANSFER CHARACTERISTICS Intensification of the heat transfer quality in adsorbers is a key-factor for development of dynamically efficient adsorption refrigeration and heat pump systems λeq= 0.09 W/m K • WHTC= 10 W/m2 K λeq=0.4 W/m K • WHTC= 100-400 W/m2 K λeq= 10 W/m K • WHTC= 20 W/m2 K λeq=0.6 W/m K • WHTC= >1000 W/m2 K Coated adsorbers DEVELOPMENT STEPS Grains - coating - synthesis SUMMARY Basics Current market Situation R&D priorities Novel Adsorbent Materials Adsorbent coatings Adsorption machine components Machine optimization and control Recent advancement at CNR-ITAE Components for Adsorption Machines Utilization of compact, lightweight, high surface area HEXs is mandatory for realization of dynamically efficient adsorbent beds Optimization of the HEX • (H&M transfer properties, thermal mass, flow field) design Optimal configuration of the “adsorbent – HEX” (AdHex) unit Corrosion • Optimal adsorbent mass per 1 m2 of HEX • Optimal size of the adsorbent Is it a real issue? Coatings offer a barrier effect Components for Adsorption Machines Increased dynamic efficiency of the AdHex unit asks for compact and efficient evaporator and condenser The heat transfer between tube wall and refrigerant and between tube wall and chilled water circuit have to be increased through: o Increasing of the specific surface area o Improvement of the heat transfer coefficient o Increasing the volume flow and the turbulence inside the tube a a a SUMMARY Basics Current market Situation R&D priorities Novel Adsorbent Materials Adsorbent coatings Adsorption machine components Machine optimization and control Recent advancement at CNR-ITAE Machine optimization IMPROVED CYCLES Thermal wave Heat and/or mass recovery Cascades cycles Multiple beds Today the trend is to use low regeneration T. Most developers are using the simple cycle, especially for low temperature applications Machine optimization Bed 1 MANAGEMENT STRATEGY Isosteric Isosteric Desorption Adsorption Adsorption Bed 2 Isosteric Desorption Isosteric UP TO 30% COP INCREASING Very short duration of the isoteric stages Identification of the optimal cycle time for a given operating condition Desorption rate is faster than adsorption, due to higher temperature and vapor pressure SUMMARY Basics Current market Situation R&D priorities Novel Adsorbent Materials Adsorbent coatings Adsorption machine components Machine optimization and control Recent advancement at CNR-ITAE ITAE’s Coating Technique Inorganic (clay-based) binder Organic binder collaboration UNIME – in with Preparation of the Coated Adsorbers Coating technique: The original lamella HEX in aluminum was coated by pouring a SAPO-34 zeolite – polymeric binder (5 wt.%) solution through the lamellas … …drying at room temperature, then heating at 120 °C in oven. • binder thermally resistant in the T-range of application • coating thickness can be controlled (0.1- 0.7 mm) by multi-layer deposition The prepared adsorbers ITAE coating performance evaluation HEX filled with grains 10 10 20 Coated HEX Cycle time, min Wall Heat Trans. Coeff., W/m2K Specific cooling power W/kgads 5 100 300 Adsorption Chiller for Automotive Applications Thermally OPerated Mobile Air Conditioning Systems TORINO Overall volume 150 L Overall weight 59 kg Chilling capacity 2,3 kW Min, air temperature 9 °C COP 0,2 Regeneration temp. Adsorbent 80 °C Zeolite o SCP: up to 600 W/kg o Very competitive weight considering commercial products! o Volume density higher than 10kW/m3! Prototype 57 cm STRALIS 520 Cabin installation Solar Cooling System for Residential Application Technology of solar thermal collectors Number of evacuated tubes Total thermal collectors area [m2] Heat storage volume [m3] Tilt angle [°] Gas Boiler nominal Power [kW] AHP cooling Power [kW] Required Cooling Load [max, kW] Cold delivering system Overall radiant surface [m2] Evacuated tubes 90 9.6 0.5 20 20 8 2.43 Flat radiant panel 28 Test facility for Trigeneration Systems • 75 kW heat source up to 99 °C • 15 – 50 °C discharging T ability • 2 – 20 °C Low T simulation ability • 1500 litres High Temperature High Temp Storage 99°C Heat Source Storage • 1000 litres Low Temperature Storage • Variable flow hydraulic pumps • High accuracy sensors • Pressure drop measurements • Full automatic operation Management/ measurements Low Temp. Storage System under testing (overnight tests!) • UNI-EN 12977 – III (possible tests on storages for solar application) Piping Testing of chillers up to 35-40 kW cooling Thermal energy storage test (max charging rate 75 kW – discharging 63 kW ICE or Fuel cell Cogenerator Conclusions Development will be mainly technological Better materials Enhanced heat transfer/HEX Optimized management strategy Techno-economic optimization Scientific issues Material science (adsorbents, etc.) From thermodynamic to adsorption dynamics Thank you!