Energy Efficient Hot and Chilled Water Generator

Introduction

Utilities at any industrial manufacturing center are a direct cost and constant strain on profitability. Three of the most commonly used utilities are steam, hot water, and chilled water. Steam is usually generated by a boiler (electric, natural gas, or fuel oil) and chilled water is generated by a electric chiller utilizing a common refrigeration cycle. Using the steam to heat water in a heat exchanger then typically generates hot water.

If you're plant uses hot water and chillers, you'll be pleased to learn that there is a commercially available, proven technology to dramatically lower your utility costs associated with these utilities with a payback averaging 1 1/2 to 2 years.

Figure 1: ThermoSorber™ Cuts Energy Costs

The Thermally Powered Heat Pump / Chiller

The best summary of the technology is that you input ambient water, low pressure steam (50 psi or higher), and minimal electricity for pumping. You get water delivered at a minimum temperature of 110 °F (maximum temperature of 160 °F) and chilled water as low at 34 °F. All the while, you're saving about 30% of the cost of producing hot water and 90% of the energy needed to produce chilled water.

So, how does it work? The ThermoSorber™ uses an old thermal cycle fluid (ammonia) in a new way. By utilizing a rectifier and a generator together along with a condenser, absorber, and an evaporator, each "unit" of steam is used to produce 1 + 0.60 units of hot water and 0.60 units of chilled water. Essentially, the ThermoSorber™ produces hot water at 156% efficiency. Chilled water is produced as a by-product of the heat pumping action without any further energy inputs outside of pumping ammonia/water solution. The cycle begins with a solution of ammonia and water, which is pressurized and heated to generate ammonia gas, and desorbed liquid. The gas is condensed, releases heat, and is then expanded to low pressure to produce a vapor and cooling. The resulting ammonia vapor is absorbed back into the desorbed liquid to produce a solution and additional heating. Now, the solution is pumped back to the generator. The ThermoSorber™ supplements that cycle with proprietary heat and mass exchangers.

Here are some example inputs and outputs from an installation at a large poultry processing plant. The ThermoSorber™ delivers 350 kW of chilling capacity and 930 kW of hot water capacity from 580 kW of steam. The chilled water is delivered at 41 °F and the hot water is at 137 °F.

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The ThermoSorber™ shown in Figure 5 was installed at a meat packing plant in Green Bay, Wisconsin. It produces 10.5 million Btu/h of 145 °F hot water plus 300 tons (1000 kW) of 34 °F chilled water. The feed steam rate is 7,500 lb/h at 100 psig