Solar Industrial Process Heat Systems Research Articles

Techno-economic and environmental feasibility analysis of solar industrial process heating systems in textile industries of Bangladesh

Taking into account the energy crisis and concerns about the effect of burning fossil fuels on the environment, the utilization of renewable energy technologies is being promoted extensively. Despite having significant potential, the feasibility of utilizing solar thermal energy as industrial process heat in Bangladesh is yet to be assessed and this paper aims to fill this research gap. In current work, the viability of utilizing solar thermal energy in Bangladesh for industrial process heating is investigated by parametric analysis considering thermal, economic, and environmental factors. Effect of mass flow rate and inlet temperature on overall heat loss coefficient is studied. The heat gain with respect to the available area for different mass flow rates is presented which can be used as a guideline to determine the capacity of an installed system. A case study is presented for an operational textile factory in Mymensingh to realize the potential of solar industrial process heat using flat plate solar collectors. Energy savings might reach up to 14.7% in summer and around 9% in winter which also leads to reduction of CO2 emission to the same percentage. The payback period has been found to be 13.58 years.

A potential solution in reducing the parabolic trough based solar industrial process heat system cost by partially replacing absorbers coatings with non-selective ones in initial loop sections

An important step to achieve low-emission production is the integration of solar energy into industrial processes for decarbonizing the industrial sector. It is therefore necessary to attempt to minimize the cost of these solar industrial process heat systems. The article presents a strategy to reduce the investment costs and thus increase the popularity of parabolic trough collectors by partially replacing the expensive selective coating with a high absorptive, low-cost, non-selective coating in the initial sections of the solar loop where the heat transfer fluid temperature is lower. The analysis was performed for 4 case studies reflecting commercially available solutions with varying temperature ranges for different industrial applications. Calculations were performed using the two-dimensional developed mathematical model that validated with experimental data. The assumed heat transfer fluid is Therminol VP-1. The results have shown the potential of partial use of the Pyromark coating for low and medium-temperature industrial process heat systems with inlet–outlet temperature ranges of 60–120 °C and 100–200 °C. The analysis also showed that all the absorbers can be covered with a low-cost coating in the first scenario. Efficiency increases from 1.5 to 5.5 percentage points have been observed. For the second scenario, 15 of the 24 absorbers can be covered with a low-cost coating, when the installation works at a solar irradiance of 800 W/m2. Since the results are depended on the solar irradiance and the chosen regulation strategy of the flow, the final number of absorbers possible to cover with non-selective coating requires a long-term analysis for each case examined.

Economics of Implementing Solar Thermal Heating Systems in the Textile Industry

This paper analyzes the potential of solar thermal systems for being employed for process heating in cotton-based textile industries. The technological capability of a flat plate collector (FPC) to meet the solar industrial process heating (SIPH) requirement in yarn production is assessed. Moreover, the usability of a parabolic trough collector (PTC) in meeting the technological mandates of SIPH in fabric processing units is critically examined. Further, this paper reports the findings of a study on the potential cost advantage of solar process heating over the conventional process heating practices in cotton-based textile industries. The approach involves the selection of the locations of sample textile industries and the employable solar collector technologies, as well as assessment of financial reward, if any. Eight different cotton-based textile industries located in different geographical domains (in India) are selected. The selected textile industries are situated within the textile hubs existing in different states across India. Analysis of technoeconomic benefit derivable in selected textile industries using FPC for hot water generation and PTC for steam generation is presented. In the case of FPC-based SIPH systems, the maximum value of solar fraction is estimated to be 0.30 and the corresponding estimation for the levelized cost of useful thermal energy (LCUTE) delivered comes out as INR 790/GJ to INR 1020/GJ. On the other hand, in case of parabolic-trough-solar-concentrator-based SIPH systems, LCUTE is estimated in the range of INR 1030/GJ to INR 1610/GJ. From a critical analysis of financial viability in consideration of related factors such as payback time and return on investment in SIPH, it appears that the SIPH systems for hot water generation may be a good choice, whereas SIPH systems for steam generation are seen to have longer payback periods and lower returns on investment, and, therefore, it seems that adequate financial support from central and state governments with additional supports from bilateral or multilateral organizations may enable them to become a sustainable technology option.

Integration of Solar Process Heat in Industries: A Review

Industrial manufacturing approaches are associated with processing materials that consume a significant amount of thermal energy, termed as industrial process heat. Industrial sectors consume a substantial amount of energy for process heating over a wide range of temperatures (up to 400 °C) from agriculture, HVAC to power plants. However, the intensive industrial application of fossil fuels causes unfavorable environmental effects that cannot be ignored. To address this issue, green energy sources have manifested their potential as economical and pollution-free energy sources. Nevertheless, the adoption of solar industrial process heating systems is still limited due to a lack of knowledge in the design/installation aspects, reluctance to experience the technical/infrastructural changes, low price of fossil fuels, and lack of relative incentives. For successful solar process heat integration in industries, a proper understanding of the associated design factors is essential. This paper comprehensively reviews the integration strategies of solar industrial process heating systems, appraisal of the integration points, different aspects of solar collectors, installed thermal power, and thermal storage volume covering case studies, reports and reviews. The integration aspects of solar process heat, findings, and obstacles of several projects from the literature are also highlighted. Finally, the integration locations of SHIP systems are compared for different industrial sectors to find out the most used integration point for a certain sector and operation. It was found that for the food, beverage, and agriculture sector, 51% of solar process heat integration occurs at the supply level and 27.3% at the process-level.

Life-cycle assessment of solar integrated mining processes: A sustainable future

The negative impact of the mining industries on climate change, human health and ecosystems, arises from extensive use of fossil fuels. This could be mitigated by the integration of solar energy systems into mining processes, such as the use of solar industrial process heating systems in low-temperature mining processes. This paper estimates the resultant environmental impacts, which could result from the partial use of solar process heating in the aluminum, copper, ilmenite, rutile, lead, nickel, and uranium mining and extraction processes. The extensive analysis presented here contains multiple scenarios such as using flat plate solar collector and evacuated tube solar collector for process heat generation, including the base case scenario using fossil fuels. The novel analysis has quantified the overall reduction of environmental impacts on different categories of aquatic ecotoxicity, terrestrial ecotoxicity, carcinogens, non-carcinogens, and global warming. The analysis is done using SimaPro (version 8.5) utilising the IMPACT 2002 + method for 15 midpoints indicator-based categories and four endpoint indicator-based categories. The analysis results reveal valuable information regarding comparative impacts between the two types of solar collector considered and show that evacuated tube collectors would be more beneficial for environmental emission reduction.

Financial viability of solar industrial process heating and cost of carbon mitigation: A case of dairy industry in India

Dairy industry in India has a substantial demand for process heating at temperatures that can be provided with solar collectors. However, the acceptance and dissemination of solar industrial process heating systems would also be affected by their financial attractiveness for the users. Another attractive feature of SIPH systems is their ability to mitigate environmental emissions. Results of a financial viability analysis including estimation of cost of mitigating carbon emissions with use of SIPH in dairy industry in India are presented in this paper. Seven locations in India with dairy plants have been selected and annual useful thermal energy output of SIPH systems at these locations has been estimated. Further, levelized unit cost of useful thermal energy (LCUTE) delivered by the SIPH systems is estimated and a comparison with the existing process heating options being used in the dairy industry in India have been made. Other measures of financial viability such as discounted payback period, net present value and internal rate of return for an investment in SIPH systems in dairy plants have also been estimated. Finally, the cost of carbon mitigation with use of SIPH in dairy industry in India has been estimated. Results presents that in terms of LCUTE solar industrial of process heating systems doesn’t seems financially viable. Moreover, payback period of the SIPH systems are very higher thus lower value of NPV and IRR, therefore, their use does not seem to be much attractive. Also the cost of carbon emissions likely to be mitigated with use of SIPH is on higher side. Therefore, In view of the long term economic and environmental benefits of using SIPH in dairy industry there is a need of marginal support to ensure their financial viability as compared to fossil fuel based systems, the government may consider providing suitable incentives for the same.

Incentives for promotion of solar industrial process heating in India: a case of cotton-based textile industry

An approach to estimate the required extent of incentives so as to make solar industrial process heating (SIPH) financially competitive with conventional process heating system for cotton-based industry in India has been presented. The levelized cost of useful thermal energy (LCUTE) delivered by the conventional (furnace oil based) and SIPH systems in cotton-based textile industry in India has been estimated. The estimates for the LCUTE of SIPH systems vary from Rs 1035 to Rs 1392 per GJ, and the same are relatively higher than the corresponding estimate for the furnace oil-based process heating system (Rs 924 per GJ), thus justifying the provision of incentives in the initial phase. Frameworks have been developed to estimate the extents of each of the incentives required to make SIPH systems financially competitive with the existing furnace oil-based process heating systems (in terms of LCUTE). From the results, it is noted that the required amounts of viability gap funding (capital subsidy) vary from 8 to 34% of the capital cost, while the required rates of interest on the debt component vary from 3.3 to 9.5% at different locations having clusters of cotton-based textiles in India. Similarly, the required rate of investment tax credit for the investment made on SIPH system varies from 8.6 to 37%.

Effect of incentives on the financial attractiveness of solar industrial process heating in India

India has a huge industrial demand for process heating at temperatures that can be provided with commercially available solar collectors. Government of India with support from multi-lateral agencies has initiated an ambitious programme for promoting large scale adoption of Solar Industrial Process Heating (SIPH) in the industrial sector of the country. This paper presents the details of an attempt to study the effect of several existing and potential incentives on the financial attractiveness of SIPH systems in India. A case of solar process heating in dairy industry has been presented to demonstrate the relative efficacy of different incentives on the economics of SIPH systems in terms of their impact on levelized cost of useful thermal energy delivered. Finally, policy implications of the results obtained have been discussed.

GHG mitigation potential of solar industrial process heating in producing cotton based textiles in India

A preliminary attempt to estimate the potential of solar process heating in producing cotton based textiles in India as well as the amount of greenhouse gases likely to be mitigated consequently has been made. To begin with, all the processes involved in the production of cotton based textiles (yarn and cloth) that require thermal energy have been identified. Also an assessment of availability of solar radiation as well as the ambient conditions at various locations with clusters of cotton based textile units in the country has been made. Subsequently, the solar collector area required for meeting the process heating demand has been estimated. Further, corresponding useful thermal energy delivery of solar industrial process heating systems at identified locations has been estimated. The process heating potential in term of useful thermal energy requirements in cotton based textile production is estimated at 191 PJ annually. The estimated values of annual solar fractions for the identified locations with clusters of cotton based textile units range between 0.22 and 0.32 for systems without storage and in between 0.20 and 0.60 for SIPH system having provision of thermal storage for collection of energy that would otherwise be dumped. Solar process heating in cotton based textile industry in India have a potential to mitigate 2457–7648 thousand tonnes of greenhouse gas emissions annually depending on the location and the provision of a storage component or otherwise.

Carbon mitigation potential of solar industrial process heating: paper industry in India

A simple framework to estimate the potential of solar industrial process heating (SIPH) and corresponding CO2 emissions mitigation in paper industry in India is presented. Geographical locations with clusters of paper mills have been identified and the annual process heating requirement for paper production (based on raw material use) at each cluster has been estimated. The total process heating potential for the paper industry in India has been estimated at 25.2 PJ/annum. Using the estimated performance of a commercially available parabolic trough based SIPH system with collector area requirement of 1.11 million m2 annual solar fraction in the range of 0.25–0.30 have been estimated. Annual energy delivery of SIPH systems estimated at 4.34 PJ per annum. Finally at 8 main locations with clusters of paper mills in India considered in this study, adoption of SIPH without storage is expected to mitigate 0.34 million tonnes of CO2 emissions annually.

The energy subsidisation policies of Cyprus and their effect on renewable energy systems economics

In this paper, the energy subsidisation policies that are in effect in Cyprus are investigated with respect to their effect on renewable energy systems economics. Two subsidisation policies are investigated, those of renewable energy and fuels. These are contradictory, as one is in favour and the other is against the exploitation of renewable energies on the island, which is the declared Government policy. First, the policy measures are described and their effect on the economic viability of a solar system is investigated by means of an example. This concerns a solar industrial process heat system for which four types of collectors are considered. From the results presented it is clear that renewable energy subsidies create a positive impulse on renewable energies whereas the economic factors improve considerably when the subsidy for fuel is removed, as the expenditure made for the erection of a solar system replaces a more expensive fuel.

Solar energy potential for heating and cooling systems in big cities of Turkey : Şaylan, L. et al. Energy Conversion and Management, 2002, 43, (14), 1829–1837

The thermal utilization of solar energy is usually confined to domestic hot water systems and somewhat to space heating at temperatures up to 60 °C. Industrial process heat has a considerable potential for solar energy utilization. Cyprus has a small isolated energy system, almost totally dependent on imported fuels to meet its energy demand. The abundance of solar radiation together with a good technological base, created favorable conditions for the exploitation of solar energy in the island. The number of units in operation today corresponds to one heater for every 3.7 people in the island, which is a world record. Despite this impressive record no solar industrial process heat system is in operation today. The main problem for this is the big expenditure required for such a system and the uncertainty of the benefits. The objective of this work was to investigate the viability of using parabolic trough collectors for industrial heat generation in Cyprus. The system is analyzed both thermally and economically with TRNSYS and the TMY for Nicosia, Cyprus, in order to show the magnitude of the expected benefits. The load is hot water delivered at 85 °C at a flow rate of 2000 kg/h for the first three quarters of each hour from 8:00–16:00 h, 5 days a week. The system consists of an array of parabolic trough collectors, hot water storage tank, piping and controls. The optimum collector area for the present application is 300 m2, the optimum collector flow rate is 54 kg/m2 h and the optimum storage tank size is 25 m3. The system covers 50% of the annual load of the system and gives life cycle savings of about C£6200 (€10800). This amount represent the money saved from the use of the system against paying for fuel. The savings however refer to a non-subsidized fuel price, which will be in effect from 2003. The optimum system can deliver a total of 896 GJ per year and avoids 208 tons of CO2 emissions to the atmosphere. The effect of various design changes on the system performance was investigated. The E–W tracking system (collector axis aligned in N–S direction) was found to be superior to the N–S one. The required load temperature affects the performance of the system as for higher temperatures the auxiliary energy required is bigger. Also a number of variations in the load use pattern have been investigated and presented in this paper. It was found that the bigger the load (double shift, full hour use pattern) the bigger the collector area required, the greater the first year fuel savings and the greater the life cycle savings of the installation. This means that it is more viable to apply solar industrial process heat to higher energy consumption industries.

Parabolic trough collectors for industrial process heat in Cyprus

The thermal utilization of solar energy is usually confined to domestic hot water systems and somewhat to space heating at temperatures up to 60 °C. Industrial process heat has a considerable potential for solar energy utilization. Cyprus has a small isolated energy system, almost totally dependent on imported fuels to meet its energy demand. The abundance of solar radiation together with a good technological base, created favorable conditions for the exploitation of solar energy in the island. The number of units in operation today corresponds to one heater for every 3.7 people in the island, which is a world record. Despite this impressive record no solar industrial process heat system is in operation today. The main problem for this is the big expenditure required for such a system and the uncertainty of the benefits. The objective of this work was to investigate the viability of using parabolic trough collectors for industrial heat generation in Cyprus. The system is analyzed both thermally and economically with TRNSYS and the TMY for Nicosia, Cyprus, in order to show the magnitude of the expected benefits. The load is hot water delivered at 85 °C at a flow rate of 2000 kg/h for the first three quarters of each hour from 8:00–16:00 h, 5 days a week. The system consists of an array of parabolic trough collectors, hot water storage tank, piping and controls. The optimum collector area for the present application is 300 m 2, the optimum collector flow rate is 54 kg/m 2 h and the optimum storage tank size is 25 m 3. The system covers 50% of the annual load of the system and gives life cycle savings of about C£6200 (€10800). This amount represent the money saved from the use of the system against paying for fuel. The savings however refer to a non-subsidized fuel price, which will be in effect from 2003. The optimum system can deliver a total of 896 GJ per year and avoids 208 tons of CO 2 emissions to the atmosphere. The effect of various design changes on the system performance was investigated. The E–W tracking system (collector axis aligned in N–S direction) was found to be superior to the N–S one. The required load temperature affects the performance of the system as for higher temperatures the auxiliary energy required is bigger. Also a number of variations in the load use pattern have been investigated and presented in this paper. It was found that the bigger the load (double shift, full hour use pattern) the bigger the collector area required, the greater the first year fuel savings and the greater the life cycle savings of the installation. This means that it is more viable to apply solar industrial process heat to higher energy consumption industries.

Simulation studies on the steady-state performance of a dryer operating on solar energy and flash steam

This paper presents the steady-stage characteristics of a continuous dryer operating on a hybrid energy system of solar energy and flash steam. Because of its unique feature of combining an inexhaustible renewable energy source and exhaust energy from high-pressure condensates by way of flash steam, the “SOLEX” system has potential for the continuous use of solar industrial process heat systems without heat storage, as well as energy conservation. Based on a mathematical model incorporating all the subsystem descriptions over a wide parameter space, a computer simulation was carried out to obtain the performance characteristics. An economic analysis of the viability of the system indicates that the unit cost of the collector is an important parameter in determining the cost effectiveness. An optimum area of solar collector exists depending on the relative cost of steam and solar collectors

Design Approaches for Solar Industrial Process Heat Systems

Design Approaches for Solar Industrial Process Heat Systems

Temperature Control of Line-Focus Solar Collectors

Solar thermal electric power and industrial process heat systems may require a constant outlet temperature from the collector. This temperature may be efficiently maintained by adjusting the circulating fluid flow rate. Using frequency response techniques, simple relations are developed which relate controller tuning constants to collector construction and field layout. Successful controller tuning is shown to be a compromise between good response at high flow rates and stability at low flow rates. The rules of thumb are then tested by performing dynamic numerical simulations of a collector row with flow rate control.

Analytical Dynamic Modeling of Line-Focus Solar Collectors

Solar thermal electric power and industrial process heat systems may require a constant outlet temperature from the collector field. This constant temperature is most efficiently maintained by adjusting the circulating fluid flow rate. Successful tuning of analog or digital controllers requires a knowledge of system dynamics. Models relating deviations in outlet temperature to changes in inlet temperature, insolation, and fluid flow rate illustrate the basic responses and the distributed-parameter nature of line-focus collectors. When plotted in dimensionless form, the frequency response of a given collector is essentially independent of the operating conditions, suggesting that feedback controller settings are directly related to such easily determined quantities as collector gain and fluid residence time.

Analytical modeling of line focus solar collectors

Solar thermal electric power generation systems and industrial process heat systems generating steam through flash vaporization require a constant outlet temperature from the collector field. This constant temperature is most efficiently maintained by adjusting the circulating fluid flow rate. Successful design of analog controllers for this regulation requires knowledge of system dynamics and the nonlinear nature of the system parameters. Simplified models relating deviations in outlet temperature to changes in inlet temperature, insolation, and fluid flow rate illustrate the basic responses and the distributed-parameter nature of line focus collectors. Detailed models are used to develop transfer functions and frequency response curves useful for design.