Nanofluids for Air-Conditioning

Cooling Better With Nanotechnology

Ultrahigh-performance cooling is one of the most vital needs of many industrial technologies. However, inherently low thermal conductivity is a primary limitation in developing energy-efficient heat transfer fluids that are required for ultrahigh-performance cooling.

Modern nanotechnology can produce metallic or nonmetallic particles of nanometer dimensions.These nanomaterials have unique mechanical, optical, electrical, magnetic, and thermal properties. Nanofluid technology is a new interdisciplinary field of great importance where nanoscience, nanotechnology, and thermal engineering meet, has developed largely over the past decade. Nanofluids are engineered by suspending nanoparticles with average sizes below 100 nm in traditional heat transfer fluids and in our case, water. We disperse a very small amount of Carbon Nano Tube ( GNP) and Silver (Ag) nanoparticles uniformly and suspended stably in water. 

Our AQUA+ nanoparticle fluid suspensions is a new class of nanotechnology-based heat transfer fluid that exhibits thermal properties superior to water. Our goal with AQUA+ is to achieve the highest possible thermal properties at the smallest possible concentrations by uniform dispersion and stable suspension of nanoparticles in water. Although AQUA+ , an invention jointly developed by Blue Snow Energy and a partner University, is still in its final testing phases and commercialization is expected by the end of 2017.

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Nanofluids for Air-Conditioning

Central air conditioning systems serve multiple spaces from one location. These typically use chilled water as a cooling medium and use extensive ductwork for air distribution.

A District Cooling System plant that serves multiple buildings is a super central air-conditioning system. The system is typically segmented into three major subsystems:

  • the chilled water plant
  • the condenser water system (or heat rejection system)
  • the air-delivery system

The chilled water system supplies chilled water for the cooling needs of all the building’s air-handling units (AHUs). The system includes a chilled water pump which circulates the chilled water through the chiller’s evaporator section and through the cooling coils of the AHUs. 

Water is a much better heat transfer medium than air. When we move air-delivery system from conventional all-air systems to air-water systems, the entire system efficiency increases tremendously. The ideal air-water systems are active chilled beams that when properly designed and installed, can reduce energy consumption by about 30-50% compared with conventional all-air systems (25%-35% if based on ASHRAE 90.1 baseline). When active chilled beam systems remove space sensible heat with water and with a much smaller air volume, the fan power required is tremendously reduced.

The above efficiency improvements are based on water. With AQUA+ , these efficiencies are expected to improve by another 20 to 25%.

Applications In Air-Conditioning Systems

AQUA+ can be used in the following potential cooling applications that currently use water as a heat transfer medium:

AQUA+ Research

How is AQUA+ produced
The nanocomposite is prepared by chemical synthesis of functional Carbon Nano Tube (CNT) and Silver (Ag) both having high thermal conductivity. Nanofluids were prepared by dispersing different weight concentrations of CNT–Ag nano composite in distilled water.
The CNTs are treated covalently with clove buds in one pot using a free radical grafting reaction. The clove-treated CNTs (C-CNTs) are then dispersed in distilled water (DI water) resulting in C-MWCNT-DI water nanofluids. The effectiveness of the functionalization process is then verified using Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). UV–vis spectroscopy is also used to examine the stability of AQUA+ in the base fluid.
Abstract Image
Our experimental data showed that, thermal conductivity is improved by more than 22% and viscosity enhanced by 1.3-times at 0.1% particle weight concentration at a temperature of 40 deg C. 
At our critical % of nanofluid the thermal conductivity improvement reaches even to about 33% at the Reynolds number of 7,500, respectively. The increase of friction factor is negligible when compare to the advantages of heat transfer enhancement.
All experiments are compared to normal distilled water as a baseline. 

AQUA+ Production

The production of AQUA+ is only at laboratory scale as graphene is still expensive but we see the prices trending down. Design efforts are on the way to make a commercial scale production rig for  AQUA+ that can be mobile as well.

The mobile AQUA+ Generation Plant will convert CNT to AQUA+ at site for injection into Chilled Water Plants. It will also have ‘ dialysis ‘ machine to remove the existing chilled water , carry out water treatment and and prepare the system for AQUA+ infusion

Please contact [email protected] for a dialogue for future partnerships