A Lithium Bromide Absorption Chiller with Cold Storage
Abstract
A LiBr-based absorption chiller can use waste heat or solar energy to produce useful space cooling for small buildings. However, operating this absorption chiller at high ambient temperatures may result in performance degradation, crystallization in the absorber, and high water consumption for heat rejection to the ambient. To alleviate these issues, a novel LiBr based absorption chiller with cold storage is proposed in this study. The cold storage includes tanks for storing liquid water and LiBr solution, associated piping, and control devices. The cold storage allows shifting heat rejection to the periods with lower ambient temperatures such as nighttime. The difference between the ambient temperatures at nighttime and daytime could be significant in many areas of the world. An ambient temperature reduction of 10 deg C could increase the single-effect absorption cycle COP (Coefficient Of Performance) from 0.71 to 0.75. Alternately, if the COP is kept the same, this ambient temperature reduction can lead to a larger difference between the ambient and condenser or absorber temperature, resulting in lower water consumption for a hybrid-cooling tower or a smaller air-cooled heat exchanger for absorber or condenser. Unlike a conventional absorption chiller, the proposed system is designed to allow the LiBr solution to crystallize in the absorber. The proposed system is evaluated at a representative climate condition and cooling load profile for small buildings with in-house thermodynamic models and consistent fluid properties and assumptions. The performance, size of the storage tank, and the water consumption of the proposed system is compared to those of a conventional LiBr-based absorption chiller. A parametric study is performed to investigate the impacts of the ambient wet bulb temperature and solution flow rate on chiller performance.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 15, 2011
- Accession Number
- ADA566206
Entities
People
- Ching-jen Tang
- William Gerstler
Organizations
- General Electric