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Results for “Condensing Boilers”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Polymer heat exchanger design for condensing boiler applications

Condensing boilers achieve very high efficiency levels by recovering both sensible heat and water vapor latent heat from the flue gas. Research since the 1980's has focused on corrosion in such condensing heat exchangers related to the acidic condensate and material selection. Polymers in condensing heat exchangers have been considered to avoid the cost and corrosion concerns of metallic designs. Past efforts have shown that polymers offer the advantage of corrosion resistance and cost, however, lower thermal conductivity limited their application. More recent developments have introduced thermally conductive polymers which now offer promising conductivity values. This project focused on the evaluation of a thermally conductive polymer heat exchanger for this application. Computational fluid dynamic results indicated thermal conductivity values of stainless steel, a typical heat exchanger material, do not need to be achieved for similar heat transfer performance. An increase in thermal conductivity from about 10 times that of the base polymer can achieve an overall heat exchanger effectiveness similar to that achieved with stainless steel. A polymer composite thermal conductivity of approximately 2.5 W/m∙K would be adequate. Thermally conductive polymer materials are now commercially available which offer values up to 20 W/m∙K. In this work, one Nylon-12 and one thermally conductive polymer composite heat exchanger prototypes were constructed for a condensing boiler application. In conclusion, tests demonstrated that good overall heat transfer performance was achieved. The lower thermal conductivity of the polymer heat exchanger will lead to higher surface temperatures and lower water condensation rates.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2013

Measure Guideline: Condensing Boilers—Control Strategies for Optimizing Performance and Comfort in Residential Applications

The combination of a gas-fired condensing boiler with baseboard convectors and an indirect water heater has become a common option for high-efficiency residential space heating in cold climates. While there are many condensing boilers available on the market with rated efficiencies in the low to mid 90% efficient range, it is imperative to understand that if the control systems are not properly configured, these heaters will perform no better than their non-condensing counterparts. Based on previous research efforts, it is apparent that these types of systems are typically not designed and installed to achieve maximum efficiency (Arena 2010). It was found that there is a significant lack of information for contractors on how to configure the control systems to optimize overall efficiency. For example, there is little advice on selecting the best settings for the boiler reset curve or how to measure and set flow rates in the system to ensure that the return temperatures are low enough to promote condensing. It has also been observed that recovery from setback can be extremely slow and, at times, not achieved. Recovery can be affected by the outdoor reset control, the differential setting on the boiler and over-sizing of the boiler itself. This guide is intended for designers and installers of hydronic heating systems interested in maximizing the overall system efficiency of condensing boilers when coupled with baseboard convectors. It is applicable to new and retrofit applications.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2013

Expert Meeting: Optimized Heating Systems Using Condensing Boilers and Baseboard Convectors

On August 11, 2011, in Denver, CO, a Building America Expert Meeting was held in conjunction with the Building America Residential Energy Efficiency Technical Update Meeting, to review and discuss results and future plans for research to improve the performance of hydronic heating systems using condensing boilers and baseboard convectors. A meeting objective was to provide an opportunity for other Building America teams and industry experts to provide feedback and specific suggestions for the planned research.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2013

Expert Meeting: Optimized Heating Systems Using Condensing Boilers and Baseboard Convectors

On August 11, 2011, in Denver, CO, a Building America Expert Meeting was held in conjunction with the Building America Residential Energy Efficiency Technical Update Meeting, to review and discuss results and future plans for research to improve the performance of hydronic heating systems using condensing boilers and baseboard convectors. A meeting objective was to provide an opportunity for other Building America teams and industry experts to provide feedback and specific suggestions for the planned research.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2014

Measure Guideline: Condensing Boilers - Optimizing Efficiency and Response Time During Setback Operation

Conventional wisdom surrounding space heating has told us a couple of things consistently for several years now: size the mechanical systems to the heating loads and setting the thermostat back at night will result in energy savings. The problem is these two recommendations oppose each other. A system that is properly sized to the heating load will not have the extra capacity necessary to recover from a thermostat setback, especially at design conditions. The implication of this is that, for setback to be successfully implemented, the heating system must be oversized. This issue is exacerbated further when an outdoor reset control is used with a condensing boiler, because not only is the system matched to the load at design, the outdoor reset control matches the output to the load under varying outdoor temperatures. Under these circumstances, the home may never recover from setback. Special controls to bypass the outdoor reset sensor are then needed. Properly designing a hydronic system for setback operation can be accomplished but depends on several factors. Determining the appropriateness of setback for a particular project is the first step. This is followed by proper sizing of the boiler and baseboard to ensure the needed capacity can be met. Finally, control settings must be chosen that result in the most efficient and responsive performance. This guide provides step by step instructions for heating contractors and hydronic designers for selecting the proper control settings to maximize system performance and improve response time when using a thermostat setback.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2015

Low Cost Polymer heat Exchangers for Condensing Boilers

Work in this project sought to develop a suitable design for a low cost, corrosion resistant heat exchanger as part of a high efficiency condensing boiler. Based upon the design parameters and cost analysis several geometries and material options were explored. The project also quantified and demonstrated the durability of the selected polymer/filler composite under expected operating conditions. The core material idea included a polymer matrix with fillers for thermal conductivity improvement. While the work focused on conventional heating oil, this concept could also be applicable to natural gas, low sulfur heating oil, and biodiesel- although these are considered to be less challenging environments. An extruded polymer composite heat exchanger was designed, built, and tested during this project, demonstrating technical feasibility of this corrosion-resistant material approach. In such flue gas-to-air heat exchangers, the controlling resistance to heat transfer is in the gas-side convective layer and not in the tube material. For this reason, the lower thermal conductivity polymer composite heat exchanger can achieve overall heat transfer performance comparable to a metal heat exchanger. However, with the polymer composite, the surface temperature on the gas side will be higher, leading to a lower water vapor condensation rate.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2015

Catalyst-Based Nonchemical Water Treatment System Frank E. Moss US Courthouse Salt Lake City, Utah

In 2012 and 2013, the US General Services Administration (GSA) and Oak Ridge National Laboratory conducted an evaluation of a novel nonchemical water treatment (NCWT) system at the Frank E. Moss US Courthouse in Salt Lake City, Utah. This system purports to use a proprietary metallic catalyst to change the water’s chemistry such that hard calcite does not form on surfaces that are in contact with the water. The catalyst-based NCWT system was installed on an electric domestic water heater in the courthouse. 1 This water heater had been experiencing severe calcite buildup on the heating elements. The calcite buildup impeded heat transfer from the heating elements into the domestic water, leading to the thermostat being set excessively high in an attempt to maintain the water temperature. This caused excess heat to build up on the elements, resulting in their premature failure which required frequent replacement. The buildup also required the elements to stay energized constantly to produce enough heat to maintain temperature in the domestic hot water system. After installing the catalyst-based NCWT system, calcite buildup was dramatically reduced and failure of the elements ceased. Labor and material savings from not having to replace the elements ($\$$1,060/year) allow for less than a two-year simple payback when compared to the installed cost of the system ($\$$1,692) plus minimal annual maintenance ($\$$100/year). The catalyst-based NCWT system should be considered for deployment in any heating system that is subject to calcification, including hydronic heating systems and boilers, condensing boilers, gas water heaters, and electric water heaters. Had the catalyst-based NCWT technology not been installed on the water heater, a conventional salt-based calcite prevention system would have provided the same prevention of calcite buildup. The budget installed cost of such a system would have been $\$$3,200 plus $\$$350/year in chemicals and $\$$1,500/year labor to service the chemicals. Comparing the conventional to the catalyst-based system, the latter has both a lower installed cost and annual operating cost. The original test plan was to install the technology on both the domestic water heating system and on the site’s cooling tower, which had faced calcite issues in its history. This tower has had a calcite buildup problem that is currently being addressed with a salt-based treatment system. The project’s timeline did not allow for installing a system and testing it on the tower during the initial phase of this project in 2012 and 2013. A preliminary economic analysis was performed to estimate the installed cost and potential savings on the cooling tower. If installed on the site’s cooling tower, the installed cost of the catalyst-based system would be more expensive than the salt-based system ($\$$32,380 vs. $\$$2,700 for the salt-based). However, the salt-based system requires $\$$900/year in chemicals and $\$$3,900/year in labor, neither of which is needed by the catalyst based system. This would give a simple payback of less than seven years using the technology on a cooling tower.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

ComStock Measure Documentation: Condensing Gas Boilers

This report describes the implementation and impacts of a condensing gas boiler upgrade, which involves replacing existing boiler systems with condensing gas boilers.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2014

Measure Guideline: Condensing Boilers-Optimizing Efficiency and Response Time During Setback Operation

Conventional wisdom surrounding space heating has consistently stated two things: size the mechanical systems to the heating loads, and setting the thermostat back at night will result in energy savings. The problem is these two recommendations oppose each other. A system that is properly sized to the heating load will not have the extra capacity necessary to recover from a thermostat setback, especially at design conditions. The implication of this is that, for setback to be successfully implemented, the heating system must be oversized. This issue is exacerbated further when an outdoor reset control is used with a condensing boiler, because not only is the system matched to the load at design, the outdoor reset control matches the output to the load under varying outdoor temperatures. Under these circumstances, the home may never recover from setback. Special controls to bypass the outdoor reset sensor are then needed. Properly designing a hydronic system for setback operation can be accomplished but depends on several factors. The first step is to determine the appropriateness of setback for a particular project. This is followed by proper sizing of the boiler and baseboard to ensure the needed capacity can be met. Finally, control settings must be chosen that result in the most efficient and responsive performance. This guide provides step-by-step instructions for heating contractors and hydronic designers for selecting the proper control settings to maximize system performance and improve response time when using a thermostat setback.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2013

Optimizing Hydronic System Performance in Residential Applications, Ithaca, New York (Fact Sheet)

Condensing boiler technology has been around for many years and has proven to be a durable, reliable method of heating. Based on previous research efforts, however, it is apparent that these types of systems are not designed and installed to achieve maximum efficiency. For example, in order to protect their equipment in the field, manufacturers of low-mass condensing boilers typically recommend design strategies and components that ensure steady, high flow rates through the heat exchangers, such as primary-secondary piping, which ultimately result in decreased efficiency.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2013

Technology Solutions Case Study: Optimizing Hydronic System Performance in Residential Applications, Ithaca, New York

Condensing boiler technology has been around for many years and has proven to be a durable, reliable method of heating. Based on previous research efforts, however, it is apparent that these types of systems are not designed and installed to achieve maximum efficiency. For example, in order to protect their equipment in the field, manufacturers of low-mass condensing boilers typically recommend design strategies and components that ensure steady, high flow rates through the heat exchangers, such as primary-secondary piping, which ultimately result in decreased efficiency. There is also a significant lack of information for contractors on how to configure these systems to optimize overall efficiency. In response to these findings, researchers from Building America team Consortium for Advanced Residential Buildings worked with industry partners to develop hydronic system designs that would address these issues and result in higher overall system efficiencies and improved response times.

AFUE↗
DOE OSTI2017

Integrating Waste Heat from CO 2 Removal and Coal-Fired Flue Gas to Increase Plant Efficiency

In project DE-FE0007525, Southern Company Services demonstrated heat integration methods for the capture and sequestration of carbon dioxide produced from pulverized coal combustion. A waste heat recovery technology (termed High Efficiency System) from Mitsubishi Heavy Industries America was integrated into an existing 25-MW amine-based CO 2 capture process (Kansai Mitsubishi Carbon Dioxide Recovery Process®1) at Southern Company’s Plant Barry to evaluate improvements in the energy performance of the pulverized coal plant and CO 2 capture process. The heat integration system consists of two primary pieces of equipment: (1) the CO 2 Cooler which uses product CO 2 gas from the capture process to heat boiler condensate, and (2) the Flue Gas Cooler which uses air heater outlet flue gas to further heat boiler condensate. Both pieces of equipment were included in the pilot system. The pilot CO 2 Cooler used waste heat from the 25-MW CO 2 capture plant (but not always from product CO 2 gas, as intended). The pilot Flue Gas Cooler used heat from a slipstream of flue gas taken from downstream of Plant Barry’s air heater. The pilot also included a 0.25-MW electrostatic precipitator. The 25-MW High Efficiency System operated for approximately six weeks over a four month time period in conjunction with the 25-MW CO 2 capture facility at Plant Barry. Results from the program were used to evaluate the technical and economic feasibility of full-scale implementation of this technology. The test program quantified energy efficiency improvements to a host power plant that could be realized due to the High Efficiency System. Through the execution of this project, the team verified the integrated operation of the High Efficiency System and Kansai Mitsubishi Carbon Dioxide Recovery Process®. The ancillary benefits of the High Efficiency System were also quantified, including reduced water consumption, a decrease in toxic air emissions, and better overall air quality control systems performance.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2012

Return Condensate to the Boiler - Steam Tip Sheet #8

This revised AMO tip sheet on returning condensate to boilers provides how-to advice for improving industrial steam systems using low-cost, proven practices and technologies.

industry, manufacturing, AMO, return, condensate, ↗