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Small-scale testing of fixed-bed regenerators

Date

2021-11-30

Journal Title

Journal ISSN

Volume Title

Publisher

ORCID

0000-0002-3728-9560

Type

Thesis

Degree Level

Doctoral

Abstract

Fixed-bed regenerators (FBRs) are air-to-air energy exchangers (AAEEs) used in ventilation systems to reduce energy consumption. FBRs transfer energy by storing and releasing heat and moisture as the exchanger is cyclically exposed to different airstreams. This thesis hypothesizes that the sensible, latent, and total effectiveness of a FBR can be determined by testing a similar small-scale exchanger. The primary goal of this thesis is to develop test methods for the performance (effectiveness) evaluation of full-scale FBRs from small-scale testing. In this thesis, a small-scale test facility is developed which simulates the operation of FBRs by moving the exchanger periodically between two airstreams. Unlike other AAEEs, FBRs are transient devices in which the outlet temperature and humidity vary periodically. The effectiveness of the FBR is determined by measuring the transient outlet temperature and humidity of the air streams. Errors in effectiveness may result due to the slow response of temperature and humidity sensors and the errors depend on the time constants and location of the sensors. Methodologies to correct the errors in the measured temperature and humidity are presented and the sensible, latent, and total effectiveness results are verified with a numerical model and field test data. The average humidity measurement technique by sampling the transient outlet air, called the bag sampling method proposed by ASHRAE standard 84-2020, is also implemented and verified in this thesis. The challenge undertaken in this research was the development of a transient test facility and more flexible test methods at a lower cost per test than that presented in ASHRAE Standard 84-2020. The proposed methodology, which is especially useful during product development, does not require full-scale prototypes, large laboratories, or a high volume of conditioned airflow. In the future, this new facility and methods can be implemented to test FBRs.

Description

Keywords

fixed-bed regenerators, air-to-air energy exchanger, performance testing, HVAC, transient testing

Citation

Degree

Doctor of Philosophy (Ph.D.)

Department

Mechanical Engineering

Program

Mechanical Engineering

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DOI

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