<p>Space and water heating contribute over 50% of all the residential
building energy consumption and are especially major energy consumers in the
cold climates. Meanwhile, conventional furnaces and boilers with energy
efficiency limited to below 100% dominate the residential heating in the cold
climate, and the electric vapor-compression heat pump capacity and efficiency
decline drastically at low ambient temperatures. Thermally driven ammonia-based
chemical adsorption (chemisorption) heat pump (CSHP) systems utilize the
reversible chemical reaction between the ammonia vapor and solid sorbent to
generate heat pumping effect, which can provide heating with much higher energy
efficiency than existing cold-climate heating technologies. Despite the
significant potential of energy efficiency improvement from existing
technologies, most studies in the literature on chemisorption heat pump systems
focus on adopting the technology for refrigeration and energy storage
applications, with very limited investigations available for using the
technology for producing heating in cold climates. </p>
This thesis study is thus conducted to characterize
the operation behavior and performance of a CSHP system under cold ambient
conditions and further identify optimal design and control for such systems to
achieve high performance. In this study, both experimental and modelling
approaches are pursued to investigate a CSHP heating system from the perspective
of the sorption material using the multiple-stage LiCl-ammonia reactions, to
the novel adsorber component with hybrid heat pipe heat exchanger, and finally
to the performance of the complete heat pump system. The experimental studies
are based on a prototype CSHP system tested to identify the chemical kinetics
of the sorption material, as well as the transient performance of the adsorber
and the system. The calibrated chemical kinetics are then used in the
development of a transient adsorber model to analyze the operation and improve
design of the adsorber. The heating COP of the prototype system was measured to
be 0.75-1.16 under ambient temperatures of 8-20
C. Finally, a dynamic
system model is developed based on the dynamic models of the adsorber and other
components in the system. The system model is validated against the
experimental data and used to analyze the detailed energy flow and operation
dynamic. Based on the inefficiencies revealed by the simulation of the current
prototype system, an improved system design with reduced thermal mass and heat
loss is introduced. Simulation of the improved system results in heating COP of
1.17 to 1.23 under -13.9
C to 8.3
C ambient, respectively.
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/12739361 |
| Date | 03 August 2020 |
| Creators | Zhiyao Yang (9187337) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Relation | https://figshare.com/articles/thesis/AN_AMMONIA-BASED_CHEMISORPTION_HEAT_PUMP_FOR_COLD_CLIMATE_EXPERIMENTS_AND_MODELING_FOR_PERFORMANCE_ANALYSIS_AND_DESIGN_OPTIMIZATION/12739361 |
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