Cooling Innovation. Adsorption Heat Pumps and Chillers Recent Developments for Materials and Components

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1 Cooling Innovation Adsorption Heat Pumps and Chillers Recent Developments for Materials and Components W. Mittelbach, U. Wittstadt G. Füldner, R. Volmer, P. Bendix, L. Schnabel 1 Salvatore Vasta 2 1 Fraunhofer ISE, Freiburg, Germany, 2 CNR-ITAE, Messina, Italy

2 Adsorption Heat Pumps and Chillers: What are the main issues? Coming from the 1990: too big too heavy, too expensive Main goals over the years: reduce size, weight and price! à A high power density with low weight and high thermal AND electrical COP is needed! GbU mbh Silicagel/water adsorption chiller, Nishiyodo, Japan

3 Today s topics: Temperature range for efficient operation is defined by the working pair (adsorption material / refrigerant) à Overview working pairs Heat exchangers for adsorption/desorption à Some examples on new geometries and appropriate coating techniques Heat exchangers for evaporation/condensation become more important with advanced adsorption heat exchangers à New operation strategies/geometry Proper combination and operation in an adsorption module defines the actual performance of an adsorption heat pump à Example of a high power density adsorption module

4 Materials and refrigerants Not only ONE solution! Main selection criteria: Uptake per adsorbent mass OR volume within the temperature range of the application (heat source/sink) Ability to be applied to a heat exchanger Hydrothermal and mechanical stability Availability and costs new MOFs (e.g. Cau.10H, Mil-160)

5 Heat Exchangers for Adsorption/Desorption Combine sorbent material and heat exchanger Have to guarantee good heat and mass transfer: Thermal contact sorbent material heat exchanger Active material >> passive materials (HX metal, binder, heat transfer fluid) Porosity for good mass transfer Hydrothermal and mechanical stability Loose bed Glued Coating With binder Direct coating

6 Comparison of Adsorption HX Concepts Exchanger Type Plate-fin heat exchanger with binder based coating Fiber adsorber with direct coating Hybrid zeolite/graphite adsorber Exchanger Material aluminum aluminum graphite Adsorbent material TiAPSO SAPO-34 SAPO-34 Overall Volume [dm3] Total mass per volume (kg/dm³) Mass ratio (kg ad /kg HX ) Adsorbent filling factor (kg ad /m³)

7 Heat Exchangers for Evaporation Different options of contact HX and working fluid (Partially) flooded Falling film Thin film Operation as evaporator only: Non-stationary, but one temperature level Working fluid amount has to be controlled Evaporation of thin films very efficient! Operation as evaporator AND condenser Temperature swing, thermal mass becomes important! Condensation of thin film on HX surface à Large surface area necessary!

8 Recent Developments Evaporation HX Thin film evaporation, partially flooded: Capillary forces produce thin film on pipe Evaporation power is doubled for low filling level 1 Fiber heat exchangers: Direct condensation into the fiber structure Very thin film and high surface area à No reservoir for working fluid needed 1: Witte, Kai Thomas, DKV Jahrestagung 2009

9 How to combine? Concepts for adsorption modules + Maintenance free operation is possible + Simple construction - COP lower - Heat recovery concepts become important! + COP higher (no temperature swing in evaporator/condenser - Vacuum stability difficult (valves and connections!)

10 Recent Developments Adsorption modules ezea Fibre Size Modul / mm 800x417x x320x147 Design Performance Volume 89 Liter 34 Liter Mass zeolite appr. 9 kg appr. 3 kg operation temperature 85 C / 27 C / 19 C Nominal Cooling power 9,1 kw 6,7 kw COP (nominal) 0,48 0,47 Vol. Power density (W/l) 50 W/l 100 W/l Simple changes in geometry 135 W/l

11 Conclusions A big step forward in terms of size, weight and costs has been achieved Specific volume is reduced by a factor of 2-3 Fahrenheit launches a new product in the second half of 2017 Adsorption technology for heat transformation becomes interesting for a wide range of applications Process cooling and waste heat recovery Compact modules and low driving temperatures for cooling of high performance (HPC) data centers Hybride Chiller: Integration with compression heat pumps Mobile application

12 Thank you for your kind attention! Walter Mittelbach, CTO Fahrheit AG The funding for the development of the aluminum fiber module by the German Ministry of Economics and Energy within the project ADOSO (03ET1127) is gratefully acknowledged!