The purpose of this article was to discuss the use of adsorption chillers for waste heat recovery. The introduction discusses the need to undertake broader measures for the effective management of waste heat in the industry and discusses the benefits and technical problems related to heat recovery in industrial plants. In addition, heat sources for adsorption chillers and their application examples were described. The principle of operation of adsorption chillers is explained in the next chapter. Heat sources for adsorption chillers are indicated and their application examples are described. The above considerations have allowed the benefits and technical obstacles related to the use of adsorption chillers to be highlighted. The currently used adsorbents and adsorbates are discussed later in the article. The main part of the paper discusses the use of adsorption chillers for waste heat management in the glassworks. The calculations assumed the natural gas demand of 20.1 million m3 per year and the electricity demand of 20,000 MWh/year. As a result of conducted calculations, a 231 kW adsorption chiller, ensuring the annual cold production of 2,021 MWh, was selected. The economic analysis of the proposed solution has shown that the investment in the adsorption chiller supplied with waste heat from the heat recovery system will bring significant economic benefits after 10 years from its implementation, even with total investment costs of PLN 1,900,000. However, it was noted that in order to obtain satisfactory economic results the production must meet the demand while the cost of building a heat recovery system shall not exceed PLN 1 million.
The trigeneration systems for production of cold use sorption refrigeration machines: absorption and adsorption types. Absorption systems are characterized namely by better cooling coefficient of performance, while the adsorptive systems are characterized by the ability to operate at lower temperatures. The driving heat source temperature can be as low as 60-70 °C. Such temperature of the driving heat source allows to use them in district heating systems. The article focuses on the presentation of the research results on the adsorption devices designed to work in trigeneration systems.
Adsorption refrigeration systems are able to work with heat sources of temperature starting with 50°C. The aim of the article is to determine whether in terms of technical and economic issues adsorption refrigeration equipment can work as elements that produce cold using hot water from the district heating network. For this purpose, examined was the work of the adsorption air conditioning equipment cooperating with drycooler, and the opportunities offered by the district heating network in Warsaw during the summer. It turns out that the efficiency of the adsorption device from the economic perspective is not sufficient for production of cold even during the transitional period. The main problem is not the low temperature of the water supply, but the large difference between the coefficients of performance, COPs, of adsorption device and a traditional compressor air conditioning unit. When outside air temperature is 25°C, the COP of the compressor type reaches a value of 4.49, whereas that of the adsorption device in the same conditions is 0.14. The ratio of the COPs is 32. At the same time ratio between the price of 1 kWh of electric power and 1 kWh of heat is only 2.85. Adsorption refrigeration equipment to be able to compete with compressor devices, should feature COPads efficiency to be greater than 1.52. At such a low driving temperature and even changing the drycooler into the evaporative cooler it is not currently possible to achieve.
Searching for new refrigerants is one of the most significant scientific problems in refrigeration. There are ecological refrigerants commonly known: H2O and CO2. H2O and CO2 known as natural refrigerants, but they have problems:a high freezing point of H2O and a low triple point of CO2. These problems can be solved by the application of a hybrid sorption-compression refrigeration cycle. The cycle combines the application possibility of H2O in the high temperature sorption stage and the low temperature application of CO2 in the compression stage. This solution gives significant energy savings in comparison with the two-stage compressor cycle and with the one-stage transcritical CO2 cycle. Besides, the sorption cycle may be powered by low temperature waste heat or renewable heat. This is an original idea of the authors. In the paper an analysis of the possible extension of this solution for high capacity industrial refrigeration is presented. The estimated energy savings as well as TEWI (Total Equivalent Warming Impact) index for ecological gains are calculated.
The aim of the study was to examine the efficiency of the thermal wave type adsorption refrigerating equipment working on a pair of activated carbon and methanol. Adsorption units can work in trigeneration systems and in applications driven by waste heat. They can be built also as a part of hybrid sorption-compressor systems, and they are very popular in solar refrigeration systems and energy storage units. The device examined in this study operates in a special mode called thermal wave. This mode allows to achieve higher efficiency rates than the normal mode of operation, as a significant contributor to transport heat from one to the other adsorber. To carry out the experiment a test bench was built, consisting of two cylindrical adsorbers filled with activated carbon, condenser, evaporator, oil heater and two oil coolers. Thermal oil circulation was responsible for providing and receiving heat from adsorbers. In order to perform the correct action a special control algorithm device was developed and implemented to keep the temperature in the evaporator at a preset level. The experimental results show the operating parameters changes in both adsorbers. Obtained COP (coefficient of performance) for the cycle was 0.13.