<p>Current air conditioning systems generally
operate with a relatively fixed moisture removal capacity, and indoor humidity
conditions are usually not actively controlled in most buildings. If we focus
only on sensible heat removal, an air conditioning system could operate with a
fairly high evaporating temperature, and consequently a high coefficient of
performance (COP). However, to provide an acceptable level of dehumidification,
air conditioners typically operate with a much lower evaporating temperature
(and lower COP) to ensure that the air is cooled below its dew point to achieve
dehumidification. The latent (moisture related) loads in a space typically only
represent around 20-30% of the total load in many environments; however, the
air conditioning system operates 100% of the time at a low COP to address this
small fraction of the load. To address issues associated with inadequate
dehumidification and high energy consumption of conventional air conditioning systems,
the use of a separate sensible and latent cooling (SSLC) system can
dramatically increase system COP and provide active humidity control. Most
current SSLC approaches that are reported in the literature require the
installation of multiple components or systems in addition to a conventional
air conditioner to separately address the sensible and latent loads. This
approach increases the overall system installation and maintenance costs and
complicates the controller design. </p>
<p>A sequential SSLC system is proposed and described
in this work takes full advantage of readily available variable speed
technology and utilizes independent speed control of both the compressor and
evaporator fan, so that a single direct expansion (DX) air-conditioning (A/C)
system can be operated in such a way to separately address the sensible and
latent loads in a highly efficient manner. In this work, a numerical model of
DX A/C system is developed and validated through experiential testing to
predict the performance under varied equipment speeds and then used to
investigate the energy saving potential with the implementation of the proposed
sequential SSLC system. To realize the sequential SSLC system approach, various
corresponding control strategies are proposed and explained in this work that minimizes
energy consumption while provides active control over both space temperature
and relative humidity. At the end of this document, the benefits of applying the
SSLC system in a prototype residential building under different typical climate
characteristics are demonstrated.</p>
| Identifer | oai:union.ndltd.org:purdue.edu/oai:figshare.com:article/15065085 |
| Date | 28 July 2021 |
| Creators | Jie Ma (11191899) |
| Source Sets | Purdue University |
| Detected Language | English |
| Type | Text, Thesis |
| Rights | CC BY 4.0 |
| Relation | https://figshare.com/articles/thesis/A_SEQUENTIAL_APPROACH_FOR_ACHIEVING_SEPARATE_SENSIBLE_AND_LATENT_COOLING/15065085 |
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