Direct-fired heat pump for multi-pass water heating using microchannel heat and mass exchangers

Keinath, Christopher Mahlo

Title:

Direct-fired heat pump for multi-pass water heating using microchannel heat and mass exchangers

dc.contributor.advisor	Garimella, Srinivas
dc.contributor.author	Keinath, Christopher Mahlo
dc.contributor.committeeMember	Wepfer, William J.
dc.contributor.committeeMember	Jeter, Sheldon
dc.contributor.committeeMember	Genzale, Caroline
dc.contributor.committeeMember	Jacobs, Laurence
dc.contributor.department	Mechanical Engineering
dc.date.accessioned	2016-01-07T17:22:56Z
dc.date.available	2016-01-07T17:22:56Z
dc.date.created	2015-12
dc.date.issued	2015-08-04
dc.date.submitted	December 2015
dc.date.updated	2016-01-07T17:22:56Z
dc.description.abstract	Absorption heat pump water heaters offer improved performance compared to conventional direct-fired water heaters, with the potential for coefficients of performance well in excess of 1. A primary energy usage comparison with electric heat pumps shows that absorption systems can be competitive with current technology. However, the implementation of these systems in the residential and light commercial market has not been practical for several reasons, including a limited knowledgebase on absorption systems for this application and the lack of compact and economically viable heat and mass exchangers. An improved understanding of the coupled heat and mass transfer processes in thermally driven absorption systems to be used as heat pump water heaters was obtained over the course of this study. In addition, microchannel heat and mass exchangers that enable such compact gas-fired heat pump water heaters were developed and tested. Performance at design and off-design conditions over a range of water and ambient temperatures was simulated in detail with a system-level model developed for this purpose. The system-level model was coupled with a water-tank model to investigate several water heating scenarios including a cold start, response to a medium sized draw and response to stand-by losses. Heat and mass exchangers were designed using component-level heat and mass transfer models. The heat and mass exchangers were first installed and evaluated on a breadboard test facility. Insights from these experiments were then used to design and fabricate a monolithic unit integrating several of the microchannel heat and mass exchangers, coupled with a gas-fired desorber heat exchanger to yield a stand-alone water heater prototype. The performance of the prototype was investigated over a range of water and ambient temperatures. A comparison of results was performed to investigate the deviation between model predictions and experimental values. A refined model was developed that more accurately predicted experimental results. Energy-use and cost analyses were performed and showed the potentially significant energy savings of thermally driven heat pump water heaters.
dc.description.degree	Ph.D.
dc.format.mimetype	application/pdf
dc.identifier.uri	http://hdl.handle.net/1853/54330
dc.language.iso	en_US
dc.publisher	Georgia Institute of Technology
dc.subject	Absorption
dc.subject	Water heating
dc.title	Direct-fired heat pump for multi-pass water heating using microchannel heat and mass exchangers
dc.type	Text
dc.type.genre	Dissertation
dspace.entity.type	Publication
local.contributor.advisor	Garimella, Srinivas
local.contributor.corporatename	George W. Woodruff School of Mechanical Engineering
local.contributor.corporatename	College of Engineering
relation.isAdvisorOfPublication	7c74399b-6962-4814-9d2a-51f8b9c41e1f
relation.isOrgUnitOfPublication	c01ff908-c25f-439b-bf10-a074ed886bb7
relation.isOrgUnitOfPublication	7c022d60-21d5-497c-b552-95e489a06569
thesis.degree.level	Doctoral