Project Synopsis

Provide an independent chemical engineering peer review of a novel heat cycle developed by a licensed technology provider.

Project Summary


The client, an energy systems technology licensor, had developed a new concept for an energy storage device.  The conceived process involved two major steps – discharge and recharge.  The discharge process operates with the following steps to produce power:

  1. A working fluid which is liquid at ambient conditions at moderate to high pressures is stored in a tank at its vapor pressure.
  2. The tank is opened and the liquid is allowed to vaporize at just below its vapor pressure.  This vapor is run through an expander to produce power.
  3. After the expander, the working fluid vapor is introduced to a tank with a sorbent, where it is captured.  The sorption of the working fluid to the sorbent will generate heat, and it is expected that this heat will be used to improve the process efficiency.

To recharge the system for energy storage, the working fluid is separated from the sorbent and repressurized by:

  1. The working fluid is released (based on pressure, temperature, or other approaches) from the sorbent. The heat to drive this desorption will be delivered by either the system or the environment.
  2. The working fluid is then fed to a compressor, where it is repressurized to the liquid tank pressure.
  3. The compressed vapor is then condensed and recharged to the liquid tank for future use.

Process Engineering Associates, LLC (PROCESS) was assigned the following project responsibilities:

  • Identified potential working fluids and sorbents that would work in the client energy storage system.  Physical property data from the literature and vendors were collected and reported to the client. This included sorption of CO2 in various amines (i.e., MEA, DMEA, TEA, DEA, AEEA, DGA, Piperazine) and NH3 in various sorbents (i.e., MgCl2, CaCl2, Ionic Liquids, Aluminas).
  • Search the existing literature and patents for useful information to evaluate and classify the energy storage unit design.
  • Examined CHEMCAD models for predicting physical property data and heats of sorption for working fluids and sorbent for use in the process.
  • Developed simulations for two variants for discharge and recharge:
    • Isentropic expansion and compression were simulated with CHEMCAD.
    • Isothermal expansion and compression were derived externally and calculated in Excel.
  • Calculated mass and energy balances on all systems.
  • Determined round-turn efficiencies (power produced / power input) for various assumed process conditions.
  • Wrote sections and supported efforts to deliver a proposal for a Small Business Innovation Research (SBIR) grant from the National Science Foundation.

The results indicated that some difficulties exist in the energy balance of the system, and that the heat of adsorption/desorption may prove difficult to use effectively (especially if the energy is high).  Idealized scenarios of the process were simulated to determine preferred sorbent-working fluid properties.  The client is moving forward with presenting the technology to potential investors and building equipment for bench-scale testing.

Industry Type

  • Process Technology Licensing

Utilized Skills

  • Independent engineering review
  • Process evaluation
  • SBIR grant technical support

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