Tower Tech Closed Loop Towers and Heat Pumps

Global adoption of heat pumps is on the rise for commercial buildings. By moving heat rather than generating it, heat pumps are a highly efficient, sustainable alternative to fossil fuel systems. But heat pumps’ performance depends on having a reliable way to reject excess heat when cooling is required. A high-quality cooling tower can provide this heat removal, as long as proper care is taken to maintain purity in the pump loop. A closed circuit tower meets these purity needs. Here’s how a closed loop tower complements a heat pump system in a commercial building and the benefits of choosing Tower Tech’s closed circuit TTCC tower.

The Cooling Tower’s Role in a Heat Pump System

Cooling towers are on almost every commercial building as part of their HVAC system. Nearly all are open circuit towers, meaning the outside air and environment can come in direct contact with the water and air inside the cooling tower. To “close” an open loop tower to better work with a heat pump system, a heat exchanger would have to be added to the process. Any additional equipment adds maintenance challenges and areas of possible failure, however. This is why, for a heat pump system, the better choice is a closed loop cooling tower.

Simply speaking, a closed-circuit cooling tower is a large, outdoor heat exchanger. Inside the tower, the heat exchanger coils keep the circulating fluid inside (usually water or a mix of water and glycol) completely separate from the air that gets pulled into the tower and the water that is sprayed over the fill media. The process fluid transfers heat from the process fluid, via conduction, through the coil walls and to the outer surface. The recirculating spray water hits the coil surface, absorbing heat through latent transfer. This facilitates evaporation, enhanced by the moving air carrying rejected heat into the atmosphere. Importantly, the process fluid never comes into contact with the outside air or recirculating spray water. This keeps it clean, free from debris and protected from outside contaminants, which extends the system life and reduces the amount of chemicals needed to reduce bacteria and scale.

Hybrid operation towers like Tower Tech’s TTCC-HC, can operate in the above described “wet mode” or in “dry mode.” When running in dry mode, operates as an air-cooled tower, turning off the recirculating spray water and cooling the coils with cool ambient air. Dry mode operation provides plume abatement during cooler weather and can eliminate water loss. Even in dry mode, the process water within the coils is completely isolated.

Added to a heat pump system on a commercial building, a closed loop cooling tower safeguards against contamination in the internal process loop. Heat pumps must ensure efficient and consistent heat rejection to operate stably even in demanding conditions. Debris in the pump system has a significant, negative impact on heat pump performance. Relatedly, a closed-circuit design reduces overall maintenance and water loss. The cooling loop is isolated from the outside environment, reducing scaling, fouling and corrosion risks compared to open cooling systems. This can reduce shutdowns, extend service life and reduce unexpected operating costs.

The Difference of a Tower Tech Closed Loop Tower

Tower Tech’s TTCC tower is available in an evaporative fluid cooler model and a hybrid fluid cooler model, ideal for geographies with highly variable seasons. Both TTCC models function like all closed loop towers, chilling without direct contact between internal and external environments. What sets the TTCC apart is the Tower Tech difference.

Tower Tech towers are made of Fiber Reinforced Polymer (FRP), which is significantly lighter than metal. These factory-premade towers are delivered to sites ready to be installed, rather than requiring onsite assembly, which cuts installation time and costs. Tower Tech towers have a smaller overall footprint due to their inverted design that eliminates side louvers and mounts a series of small fans to the bottom of the tower instead of the top. Tower Tech leads the industry with a drift rating of 0.0004%, achieving significant chemical and water savings, even in open loop models.

FRP is also inherently corrosion-resistant. This helps Tower Tech towers deliver a very long service life with no rust, no corrosion and minimal maintenance beyond routine care—both outside and inside. Tower Tech’s XchangeTech coils replace the extremely heavy, corrosion-prone metal coils in conventional cooling towers. A small-diameter tube with a thin wall minimizes thermal resistance. Hundreds of these tubes – 440, to be exact – are bundled together to provide a large primary surface area for heat transfer with a very low internal pressure drop. They also have a superior impact resistance, as there are no thin fins to bend or impede performance, and they are compatible with water, glycols, brine, chlorides, oils and more. The vibration of air flowing over the polymer tubes prevent scale build up on the coils surface, further reducing maintenance while increasing longevity.

Conventional closed loop cooling tower coils are so heavy and deep within the tower that it is not uncommon for the entire tower to be replaced when the coils corrode. Tower Tech TTCC towers empower sustainable efficiency by making the coils replaceable with far less waste and no sacrifice to cooling operations. By complementing a heat pump system, a TTCC closed-circuit cooling tower by Tower Tech is the ideal partner in sustainable, cost-effective building operation.