Evaporation Unit Research Articles

Opportunities and prospects for the use of solar energy for refrigeration of public buildings

This paper describes the calculation of evaporative-radiant cooling of recycled water in summer air-conditioning systems. A differential equation for the heat balance of water flowing down an inclined plane is derived. As one possible way of increasing the efficiency of air conditioning systems based on cooling water by adiabatic evaporation in the air flow the use of night-time evaporative cooling of the water, followed by daytime cooling in insulated storage tanks. The temperature of the water chilled in this way is 3-4 °C lower than the temperature of the water chilled during the day, and the final water temperature is close to the saturation temperature of the outside air. The equations for calculation of mass transfer coefficients, radiation and heat transfer coefficient of an insulated bottom of an evaporative-radiant water-cooling unit are given. Based on the Mathcad program and the result of the calculation, the dependence of the final water temperature on the initial water temperature is obtained. As a result of the calculation, the specific heat capacity of the evaporative radiant water-cooling unit for the production of free cooling is determined.

Al-Biruni Earth Radius Optimization Based Algorithm for Improving Prediction of Hybrid Solar Desalination System

The performance of a hybrid solar desalination system is predicted in this work using an enhanced prediction method based on a supervised machine-learning algorithm. A humidification–dehumidification (HDH) unit and a single-stage flashing evaporation (SSF) unit make up the hybrid solar desalination system. The Al-Biruni Earth Radius (BER) and Particle Swarm Optimization (PSO) algorithms serve as the foundation for the suggested algorithm. Using experimental data, the BER–PSO algorithm is trained and evaluated. The cold fluid and injected air volume flow rates were the algorithms’ inputs, and their outputs were the hot and cold fluids’ outlet temperatures as well as the pressure drop across the heat exchanger. Both the volume mass flow rate of hot fluid and the input temperatures of hot and cold fluids are regarded as constants. The results obtained show the great ability of the proposed BER–PSO method to identify the nonlinear link between operating circumstances and process responses. In addition, compared to the other analyzed models, it offers better statistical performance measures for the prediction of the outlet temperature of hot and cold fluids and pressure drop values.

Study on the cost effectiveness of a combined evaporation unit

In a thermal power plant, water treatment plants are used to perform body losses in the main steam cycle using one of the following methods of water preparation: chemical, thermal, membrane or combination of them. One of the main advantages of thermal desalination is the low impact on environmental pollution. In the light of the ever-increasing environmental demands on energy processing systems, thermal desalination is becoming an increasingly preferred method of water treatment, since it allows wastewater to be used as feed water for evaporators. In our country, multi-stage evaporation units are quite widespread. They are used as operating units in industrial heating plants and as backup for condensation plants. These units have high thermal costs and are characterized by an excess of secondary vapour of the last evaporation step, which needs to be continuously removed from the plant to avoid loss of productivity. The main objective of this work is to minimize the total and thermal costs of the production of additive water in the main steam turbine cycle of the thermal power plant and the treatment of wastewater in evaporation complexes, as well as to determine the technical economic effectiveness of applying some technical solutions for the recovery of excess steam in multi-stage evaporation units.

Calculation of evaporative-radiant cooling of recycled water in summer air-conditioning systems

The paper describes the calculation of evaporative-radiant cooling of recycled water in summer air-conditioning systems. A differential equation for the heat balance of water flowing down an inclined plane is derived. One possible way of increasing the efficiency of air conditioning systems based on cooling water by adiabatic evaporation in the air flow is using night-time evaporative cooling of the water, followed by daytime cooling in insulated storage tanks. The temperature of the water chilled in this way is 3-4 ° lower than the temperature of the water chilled during the day, and the final water temperature is close to the saturation temperature of the outside air. The equations for calculating mass transfer coefficients, radiation, and heat transfer coefficients of an insulated bottom of an evaporative-radiant water-cooling unit are given. Based on the Mathcad program and the result of the calculation, the dependence of the final water temperature on the initial water temperature is obtained. As a result of the calculation, the specific heat capacity of the evaporative radiant water-cooling unit for the production of free cooling is determined.

Use of evaporative cooling units in solar air conditioning installations

The paper describes the calculation of evaporative-radiant cooling of recycled water in summer air-conditioning systems. A differential equation for the heat balance of water flowing down an inclined plane is derived. As one possible way of increasing the efficiency of air conditioning systems based on cooling water by adiabatic evaporation in the air flow the use of night-time evaporative cooling of the water, followed by daytime cooling in insulated storage tanks. The temperature of the water chilled in this way is 3-4 ℃ lower than the temperature of the water chilled during the day, and the final water temperature is close to the saturation temperature of the outside air. The equations for calculation of mass transfer coefficients, radiation and heat transfer coefficient of an insulated bottom of an evaporative-radiant water-cooling unit are given. Based on the Mathcad program and the result of the calculation, the dependence of the final water temperature on the initial water temperature is obtained. As a result of the calculation, the specific heat capacity of the evaporative radiant water-cooling unit for the production of free cooling is determined.

Optimization of excess brines disposal methods at potash mining and processing plants

The paper analyzes the positive and negative aspects of various technological solutions for the liquid brines used during the development of polymineral potash ore deposits and considers the problem of determining the choice of the optimal approach by considering geological, technical, environmental, and financial factors. The study of the issues of utilization and reduction of the liquid brines components of discharges in the production of potash fertilizers, the simultaneous reduction of valuable components loss with liquid discharges, and, due to this, increasing the production of potash fertilizers, and the usage in the technology of mine brines, are an urgent and important scientific and engineering challenge of the potash industry. Technologically, several alternative solutions can reduce the number of liquid by-products placed in sludge storage. The work used analytical methods, including statistical data processing, modeling, pre-design studies of technological solutions, and assessment of economic costs. Excess brines of potash mining and processing plants are liquid waste obtained during the production of potash fertilizers ? MOP ? SOP. The accumulation of excess brines in sludge storage facilities is estimated at millions of cubic meters per year. However, the expansion of the sludge storage facilities area and the construction of dams are only temporary solutions. They are associated with risks in the design, construction, and operation of hydraulic structures, increasing the risks of brine leakage into open and underground water basins. Therefore, it makes it necessary to use other methods of brine disposal. Depending on the nature of the processed polymineral potash ores, several methods can be combined to dispose of excess brines at once: backfilling, osmosis, injection into deep horizons, and multistage evaporation. The most optimal combination of brine reduction technologies for potassium-magnesium processing plant's raw materials is the following: 60% is disposed of by usage of vacuum evaporation units, 20 % by injecting excessive brines into deep absorbing horizons, and 10%?20% should be used for backfilling or additional products production.

Automation of the propane evaporation unit In the production of hydrogen

Automation of the propane evaporation unit In the production of hydrogen

Перспективы применения российских абсорбционных термотрансформаторов на ПГУ-ТЭЦ

The electrical power of power plants based on gas turbines (GT) decreases with an increase in air temperature and, as a result, a decrease in its mass flow at the compressor inlet. This makes it relevant to develop methods for increasing air density by lowering its temperature when wor¬king in hot arid regions and regions with a tropical humid climate. To cool the air, it is proposed to use absorption chillers (LBAC). It is shown that for air cooling in a dry hot climate, it is sufficient to use LBAC with single-stage absorption. For a humid tropical climate, where deeper air cooling is required with a simultaneous decrease in its moisture content, it is proposed to use ABCM with two-stage absorption, which are capable of producing cold at negative temperatures. To do this, it is proposed to introduce an additional evaporation and absorption unit with peri¬pheral equipment into the standard industrial design of the LBAC with single-stage absorption. Comparative energy efficiency of LBAC of standard design and LBAC with two-stage absorption during air cooling at the GT compressor inlet has been evaluated. For such critical facilities for the Russian economy as gas pumping stations using gas turbines, an LBAC unit with two-stage absorption and removal of absorption heat by water-circulating cooling systems based on cooling towers, or using air coolers (drycoolers) with the ability to turn off an additional evaporation unit if necessary, is proposed. and absorption.

Techno-economic assessment of forward osmosis as a pretreatment process for mitigation of scaling in multi-stage flash seawater desalination process

Thermal desalination processes suffer from the formation of scalants on the heat exchangers of the evaporator unit which negatively affect the process efficiency. This study evaluated the technical and economic feasibility of a pilot-scale forward osmosis (FO) process for the pretreatment of seawater to remove scaling ions before the multi-stage flash (MSF) process. A commercial hollow fiber FO membrane module was used in the pilot plant. The FO pilot plant used real seawater as feed solution and real MSF brine as draw solution. A maximum recovery rate of 27.7 % was achieved using a pressure gradient of 1.0 bar with the feed solution flowing through the membrane bore side and the draw solution flowing through the shell side with a temperature of 40 °C for both feed and draw streams. The FO membrane showed high rejection for scaling ions, where the rejection rate was almost 99 %, 96 %, and 92 % for sulfate, calcium, and magnesium, respectively. The specific power consumption of the FO process was about 0.01 kWh/m3. It was found that the water production cost for the FO process was almost 0.48 $/m3. The sensitivity analysis shows that the water production cost is highly sensitive to the water flux, especially at the lower range of water flux and high membrane cost. FO pretreatment provides a promising and economical solution for mitigating the scaling issue in MSF desalination plants.

Energy-efficient vacuum evaporation units for concentration in the dairy industry

The application of various types of evaporation plants for concentration of solutions was analyzed. It was noted that the most promising for thickening dairy products are film-type vacuum-evaporation units with mechanical compression of secondary steam. The heating chamber of the evaporator is made in the form of a vertical shell-and-tube heat exchanger with the supply of heating steam into the intertube space and with the downward movement of product solutions in the vertical boiling tubes. Based on the analysis of known studies on hydrodynamics and heat exchange of film processes (condensation, film heating and evaporation and steam separation), a conclusion was made about the lack of data for calculating pressure losses in the steam circuit of the evaporator with sufficient accuracy. To solve this problem, improved methods of calculating the hydraulic resistance of the intertube steam path of the heating chamber and the two-phase flow of the product film and secondary steam in evaporative boiling tubes have been developed using the published results of hydrodynamic resistance research. Pressure losses for the movement of secondary steam in the lower chamber of the evaporator include losses for acceleration of the steam released from the falling film of the product. It is shown that the hydraulic depression of the movement of steam in the intertube space of the heating chamber, depending on the type of scheme, can be from 2.3% to 77% compared to the working temperature pressure of the heating surfaces. The four-way flow scheme of the heating steam used in the design of the vacuum-evaporation unit ensures a reduction of hydraulic losses by up to 15%. A technical and economic analysis of the costs of operating a vacuum-evaporation unit with a productivity of 10 t/h of vaporized steam was performed, according to which the lowest reduced costs were established at a temperature drop of 5˚C on the compressor. The results of the research were used in the development of structures and the manufacture of vacuum-evaporation units with mechanical and mixed (mechanical and thermal) compression at PrJSC "Kalyniv Machine-Building Plant" (Kalynivka, Vinnytsia Region). 10 vacuum evaporation units with a capacity of 5 to 20 t/h of evaporated moisture were manufactured and put into operation.

Performance enhancement of a hybrid multi effect evaporation/membrane distillation system driven by solar energy for desalination

The development of novel and energy-efficient desalination technologies has been inspired by the global water shortage and rising fossil oil prices. The current study aimed to incorporate solar energy into a hybrid water desalination set up including thermal desalination and membrane distillation (MEE-MD) technologies. This technology was demonstrated utilizing multi-effect evaporation (MEE) and air-gap membrane distillation (AGMD) structures. The performance of the hybrid desalination system with heat recovery (MEE-HR/MD), which is powered by an evacuated tube heat pipe solar collector, was evaluated outdoors under a variety of climatic conditions. Results showed that hybrid MEE/MD configurations surpassed the standalone multi-effect evaporation unit. The performance ratio of the hybrid system is 45% higher than the standalone MEE. The hybrid proposed system has a fresh potable water production capacity of 159,84 m3 per year at a cost of US $ 5.37/m3 and minimizes carbon dioxide emissions by 189 tons per year.

Towards on energy-saving separation of ethylene glycol mixture from production plants based on energy, exergy, economic, environmental, exergoeconomic, and exergoenvironmental analyses

Reduction in energy conservation and consumption have long been research hotspots with the aggravation of energy problem. Herein, we propose a novel energy-saving method, simulated using experimental data, for separating ethylene glycol mixtures from production plants. We developed an integrated cooling and power system by driving low temperature waste heat from the proposed method, and assessed it using energy, exergy, economic, environmental, exergoeconomic, and exergoenvironmental analyses. Results showed that this novel method can reduce steam consumption by 26.11%, as compared to the currently used methods. This method showed 7.18% lower than that of the basic process, which is mostly attributed to its multi-effect evaporation unit. Economic analysis showed that the proposed system had the lowest total annual cost. And the operating cost was lower $2.45 × 105 than that of the basic process. New equipment cost of this proposed process is $10.6 × 105, accounting for 25.22% of the total equipment cost. Furthermore, environmental analysis showed that CO2, SO2, and NOx emissions as well as the integrated cooling and power system costs were decreased by 25.71%. These findings indicate that this system has a strong energy saving potential, which could accomplish clean manufacturing of ethylene glycol goods and provide a strong reference for further industrial applications.

Heat to Hydrogen by Reverse Electrodialysis—Using a Non-Equilibrium Thermodynamics Model to Evaluate Hydrogen Production Concepts Utilising Waste Heat

The reverse electrodialysis heat engine (REDHE) is a promising salinity gradient energy technology, capable of producing hydrogen with an input of waste heat at temperatures below 100 °C. A salinity gradient drives water electrolysis in the reverse electrodialysis (RED) cell, and spent solutions are regenerated using waste heat in a precipitation or evaporation unit. This work presents a non-equilibrium thermodynamics model for the RED cell, and the hydrogen production is investigated for KCl/water solutions. The results show that the evaporation concept requires 40 times less waste heat and produces three times more hydrogen than the precipitation concept. With commercial evaporation technology, a system efficiency of 2% is obtained, with a hydrogen production rate of 0.38 gH2 m−2h−1 and a waste heat requirement of 1.7 kWh gH2−1. The water transference coefficient and the salt diffusion coefficient are identified as membrane properties with a large negative impact on hydrogen production and system efficiency. Each unit of the water transference coefficient in the range tw=[0–10] causes a −7 mV decrease in unit cell electric potential, and a −0.3% decrease in system efficiency. Increasing the membrane salt diffusion coefficient from 10−12 to 10−11 leads to the system efficiency decreasing from 2% to 0.6%.

Application of organic gas steam-liquid extraction system for extraction and separation of uranium from water samples as a new efficient method

Abstract In this study, for the first time the organic gas steam-liquid extraction (OGS-LE) method is used as a simple, efficient and scalable to industrial application technique for the extraction and separation of uranium (VI) from aqueous samples. OGS-LE is done by a special handmade extraction cell. In this method, the organic solvent vapor produced in the evaporator unit is introduced into the aqueous sample by using nitrogen as a carrier gas. By inserting the vapor bubbles of the organic solvent into the aqueous sample, the organic solvent dissolves in water and the organic solvent concentration in water reaches supersaturation. During this process, equilibrium occurs between the dissolved organic solvent and the insoluble organic solvent, and it is collected on top of the aqueous phase. Uranium has been extracted with cyanex 272 and tetrabutylammonium bromide (TBAB) as extractant into n-heptane from the alkaline aqueous media by the OGS-LE method. Cyanex 272 and TBAB were used as the complexing ligand and the ion pairing reagent, respectively. The mechanism of extraction was proposed depending on the deprotonating of cyanex 272 and ionic interaction with the quaternary ammonium bases. Face Central Composite Design (FCCD) was used to evaluate the effect of various factors. Under the optimized conditions, uranium extraction could be completed in a single stage with the extraction efficiency of more than 90% from an aqueous solution containing alkali, alkaline Earth and transition metal ions. The precision, obtained by performing five replicates under the optimized conditions, was 90.12% ± 0.75% (percentage of extraction ± RSD).

Concentrating forensic DNA sample extracts on the Microlab® STARlet using the Microlab® monitored multi-flow, positive pressure, evaporative extraction module unit

A Microlab® Monitored Multi-Flow, Positive Pressure, Evaporative Extraction module ([MPE]2) unit (Hamilton Company, Reno, Nevada, USA) was installed on the Microlab® STARlet Automated Liquid Handler (Hamilton Company, Reno, Nevada, USA) to add sample concentrating capabilities to the Centre of Forensic Sciences’ automated workflow. Prior to incorporation of the [MPE]2, forensic samples extracted on the STARlet that required concentration to meet the CFS’ amplification threshold were not amplified. Filtering parameters were first optimized, then contamination was assessed, and mock casework studies were completed. There was no evidence of cross contamination or sample loss during sample concentration on the [MPE]2. Extracts from blood, envelope flaps, cigarette butts and drink container swabs were concentrated using the [MPE]2 and amplified using AmpFLSTR™ Identifiler™ Plus (Applied Biosystems™). Profiles were concordant with similar peak heights, whether concentrated manually or with the [MPE]2. Post validation, the [MPE]2 was successfully introduced into casework and in the first year an additional 450 DNA profiles, which previously would not have been amplified, were uploaded to Canada’s National DNA Databank.

Laser desorption tissue imaging with Differential Mobility Spectrometry

Pathological gross examination of breast carcinoma samples is sometimes laborious. A tissue pre-mapping method could indicate neoplastic areas to the pathologist and enable focused sampling. Differential Mobility Spectrometry (DMS) is a rapid and affordable technology for complex gas mixture analysis. We present an automated tissue laser analysis system for imaging approaches (iATLAS), which utilizes a computer-controlled laser evaporator unit coupled with a DMS gas analyzer. The system is demonstrated in the classification of porcine tissue samples and three human breast carcinomas. Tissue samples from eighteen landrace pigs were classified with the system based on a pre-designed matrix (spatial resolution 1–3 mm). The smoke samples were analyzed with DMS, and tissue classification was performed with several machine learning approaches. Porcine skeletal muscle (n = 1030), adipose tissue (n = 1329), normal breast tissue (n = 258), bone (n = 680), and liver (n = 264) were identified with 86% cross-validation (CV) accuracy with a convolutional neural network (CNN) model. Further, a panel tissue that comprised all five tissue types was applied as an independent validation dataset. In this test, 82% classification accuracy with CNN was achieved. An analogous procedure was applied to demonstrate the feasibility of iATLAS in breast cancer imaging according to 1) macroscopically and 2) microscopically annotated data with 10-fold CV and SVM (radial kernel). We reached a classification accuracy of 94%, specificity of 94%, and sensitivity of 93% with the macroscopically annotated data from three breast cancer specimens. The microscopic annotation was applicable to two specimens. For the first specimen, the classification accuracy was 84% (specificity 88% and sensitivity 77%). For the second, the classification accuracy was 72% (specificity 88% and sensitivity 24%). This study presents a promising method for automated tissue imaging in an animal model and lays foundation for breast cancer imaging.

Energy, Exergy, Exergoeconomic and Emergy-Based Exergoeconomic (Emergoeconomic) Analyses of a Biomass Combustion Waste Heat Recovery Organic Rankine Cycle.

In recent decades, there has been an increasing trend toward the technical development of efficient energy system assessment tools owing to the growing energy demand and subsequent greenhouse gas emissions. Accordingly, in this paper, a comprehensive emergy-based exergoeconomic (emergoeconomic) method has been developed to study the biomass combustion waste heat recovery organic Rankine cycle (BCWHR-ORC), taking into account thermodynamics, economics, and sustainability aspects. To this end, the system was formulated in Engineering Equation Solver (EES) software, and then the exergy, exergoeconomic, and emergoeconomic analyses were conducted accordingly. The exergy analysis results revealed that the evaporator unit with 55.05 kilowatts and the turbine with 89.57% had the highest exergy destruction rate and exergy efficiency, respectively. Based on the exergoeconomic analysis, the cost per exergy unit , and the cost rate of the output power of the system were calculated to be 24.13 USD/GJ and 14.19 USD/h, respectively. Next, by applying the emergoeconomic approach, the monetary emergy content of the system components and the flows were calculated to evaluate the system’s sustainability. Accordingly, the turbine was found to have the highest monetary emergy rate of capital investment, equal to , and an output power monetary emergy of . Finally, a sensitivity analysis was performed to investigate the system’s overall performance characteristics from an exergoeconomic perspective, regarding the changes in the transformation coefficients (specific monetary emergy).

A floating planting system based on concentrated solar multi-stage rising film distillation process

This work presents a floating planting system based on multi-stage rising film distillation process driven by concentrated solar energy. The proposed system applies desalinated freshwater to directly irrigate hydroponic crops, which saves land area and takes advantage of ocean resources. The hydrophilic wick is selected as the evaporator to form a rising seawater film by capillary suction. Through the vertically arranged multi-stage evaporation and condensation units, the latent heat of vapor can be recovered effectively. To obtain the maximum optical efficiency, the optical simulation of the concentrating section is carried out. Based on optimized structure, an experimental system is built to investigate the effects of different operating parameters on the internal temperature, water production rate, gained output ratio (GOR), and exergy efficiency. Under indoor steady-state conditions, the temperature difference of desalination units is found to be progressively larger under increasing irradiance. In addition, the system could achieve 1.7 of GOR and 6.1% of exergy efficiency with 900 W/m2 irradiance. Results at actual weather reveal that the daily water yield of the system could reach 9.51 kg/m2/day under azimuth tracking condition, which is 97% higher than the fully passive operation condition. Finally, under 28 consecutive days of operation, the average growth height of lettuces cultivated by the system is 13.7 cm.

Investigation of the Process of Simple Distillation in Irrigated Pipe Elements

In modern chemical and oil refining complexes, separation processes are among the most popular and energy-intensive. Installations for their implementation should be equipped with nodes for creating vapor (evaporators) and liquid (deflegmators) irrigation. Evaporators of any type (film, thermosiphon, gas lift, cubic) belong to this class of devices. For example, in cubic evaporators, the gas flow is completely formed from flux bubbles that originate on the heat-conducting surface and float in the volume of the cubic liquid located in the apparatus. Due to the accompanying mass exchange, the bubbles are enriched with volatile components during ascent and noticeably increase in volume, and the growth of the bubble is determined, among other things, by the total flow. At the same time, in real bubbling-type equipment, the total mass transfer surface exceeds the cross-section of the device itself by more than two orders of magnitude. Thus, according to, the ratio of the internal cross-sectional area of the apparatus to the developed mass transfer surface is 0.0015–0.002. Based on the analysis of the integral equation of the diffusion boundary layer, it is shown that the presence of a resultant flow of substance through the phase interface (non-equimolarity of the process) in a two-phase gas (vapor)–liquid system leads to the transformation of the structure of the traditional mass transfer equation itself. The use of a new structure obtained for both binary and multicomponent mixtures makes it possible to significantly simplify the approach to the description and generalization of arbitrary mass transfer processes. The innovativeness of the proposed approach lies in its universality for non-equimolar processes. This simplifies the creation of models of any mass transfer devices and entire production lines. In addition, the proposed approach is a good auxiliary tool for various researchers and experimenters. It should also be noted that the separation processes of many products of organic origin during heating are characterized by the appearance of undesirable side reactions (thermal decomposition, condensation, polycondensation, formation of harmful impurities, etc.), which occur most intensively in the heating zones. At the same time, the evaporation and distillation units are subject to requirements for the minimum hydraulic resistance of the structure, the maximum separation capacity (efficiency), and the minimum residence time of the product in the apparatus (equivalent to the minimum holding capacity of the structure). It was noted that the specified requirements are most fully met by film-type devices.

The nexus between water, exergy, and economics in an optimal integrated desalination system with two configurations and four operation modes

Numerous integrated desalination systems have been proposed to satisfy the growing global demand for freshwater. However, the responses of various optimal configurations have rarely been subject to advanced combined analyses. Here, a parallel-feed multi-effect evaporative desalination unit is integrated with a series double-effect water-lithium bromide absorption heat pump using thermo-mechanical components to propose a novel flexible system. The proposed hybrid multi-modal cooling-heating-desalination system can be configured as a single compressor or a double-compressor. Both configurations can operate in four modes, producing chilled and tap water (mode I); hot and tap water (mode II); tap water (mode III); or chilled, hot, and tap water (mode IV). The energy, exergy, and economics of the proposed system are modeled in an iterative nonlinear thermo-mathematical program. The base models are compared using exergoeconomic and novel water-exergy nexus-based evaluation criteria, their sensitivity is examined under each operation mode, and the optimal configurations are determined by solving a many-objective optimization model. A non-dominated sorting genetic algorithm generation III is employed to solve the many-objective optimization problem. Exergy for water, exergy efficiency, and total product exergy costs, respectively, improved by 3, 3.6, and 3.7 times, while total annual costs decreased by 17.8–50.3% after optimization. Considering the nexus between exergy, water, and economics, the optimal single compressor configuration was recommended for hot and dry regions and the robust double-compressor configuration was recommended for cold climates or general trigeneration.