Overview

Optimum’s Applications for the Hartman Technology

Natural Curve Sequencing of Chillers, Pumps and Towers

Power-Based Speed Control of Condenser Pumps & Tower Fans = WaterConservation

Network Control of Chilled Water Distribution Pumping

 

Overview
Optimum Energy's Engineered HVAC Performance Applications significantly reduce energy consumption, greenhouse gases, and costs without compromising occupant comfort. Using patented Hartman technologies, Optimum Energy combines these key technologies to achieve a new level of energy efficiency. Variable speed drive technology enables the major components in an HVAC system to be operated at optimum efficiency. Hartman control technologies provide an adaptive feedback loop that matches equipment operation with the cooling load on the building to optimize the operation of all components as a system, not just at the individual component level. Open standard computing and network technologies make it possible to report on plant operation and energy savings and to provide remote troubleshooting and support.

Optimum’s Applications for the Hartman Technology
To apply Optimum’s applications and Hartman technologies most effectively requires that the existing plant be converted to an all-variable speed plant by installing variable speed drives on all plant components: chillers, chilled water pumps, condenser water pumps, and tower fans. In many plants, some pumps, fans or chillers may already operate with variable speed drives. It is usually possible to retain these existing drives, which reduces the cost of the upgrade. The Hartman technologies are based on three primary principles:

Natural Curve Sequencing of Chillers, Pumps and Towers
The energy performance of constant speed chillers, pumps and tower is maximized when components are operated as closely as possible to full load. Thus, chiller plant operating strategies generally involve sequencing plant equipment to minimize the amount of on-line equipment, which is operated at full load. In all-variable speed chiller plants, optimum performance is attained when the equipment is operating at a specific part load that depends on the current external conditions. The curve of the loading at which each variable speed component achieves maximum efficiency as the external conditions (pressure or temperature) vary is called the “natural curve” of that component. Optimum’s systems employ a simple patented control methodology to sequence equipment so that plant operation is at all times as close as possible to the natural curves of the equipment contained in the plant.

Power-Based Speed Control of Condenser Pumps & Tower Fans = Water Conservation
Conventional cooling tower control involves delivering a specific (sometimes reset) condenser water temperature to the chillers.  This is usually delivered with constant speed condenser pumps.  By contrast, an all-variable speed Optimum Energy plant constantly modulates the tower fans and condenser pumps based on the load of the plant.  Because the variable speed system decreases the cycle time of the cooling tower water, water consumption can be reduced by more than 20%, in certain situations.

Network Control of Chilled Water Distribution Pumping
Chilled water distribution pumps are usually operated to maintain a specific distribution differential pressure. Sometimes this pressure setpoint is reset based on the maximum position of one or several of the valves on the loads served by the system. However, the use of minimum pressure setpoints can contribute to substantial wasted pumping energy, especially during periods of low loads, which are frequent in systems that operate on a 24/7 schedule. OptimumHVAC employs a network based method of distribution pump control that is particularly effective in large distribution circuits that may have different critical flow segments under different conditions or different times. It should be noted that at all times chillers and other components are operated within their manufacturer’s recommended limits. The Optimum Controller continuously monitors the chilled and condenser water flows and rates of flow change, as well as the condensing water temperature, and limits operation to ensure these parameters remain within the range recommended by the manufacturer for the specific chiller to which the control is applied. The automatic safety shutdown circuit on each chiller is also entirely functional in all of OptimumHVAC’s systems so that chiller protection in undiminished.

Frequently Asked Questions (FAQS)